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manner, but in the majority of instances filtration proved to bo
impossible. If, however, precipitation was made in water solu-
tion and acetic acid added later to throw out the last traces of
nickel, the oxalate came out more slowly and in a form suitable
for filtration.

The nickel sulphate taken for analysis was dissolved in water
and the solution standardized both liy precipitation as nickelic
hydroxide and ignition to the oxide and by throwing out as
metallic nickel on the rotating cathode. To a definite amount
of this solution, diluted to the required volume and heated to
boiling, was added an excess of crystallized oxalic acid. Upon
cooling, acetic acid was run in and the precipitate allowed to
settle over night. The smaller amounts of niclcel did not come
out from the water solution, and even after adding acetic acid

* Classen, Zeitschr. anal. Chem., xvi, 470.



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H. Z. Ward — Estimation of Lea d^ Nickel^.and Zinc. 337

it was necessary to heat it to start precipitation. The nickel
oxalate was filtered off on asbestos in a perforated crucible
and washed with small amounts of water. The crucible was
placed in a beaker containing about 25^"" of dilute (1 : 4) sul-

Ehuric acid and heat applied to effect the solution of the oxa-
ite. The volume of the solution was then made up to about
200*'"" and cobalt sulphate added until a slight pinkish tinge
appeared. This procedure, recommended by Gibbs, was neces-
sary to secure a definite end-point, as the green color of the
nickel masked the complementary pink of the permanganate.
The contents of the beaker were then heated to boiling and
titration made in the usual manner. The results appear in









Tablb III.






The


Determination of Nickel by Precipitation with Oxalic Acid
and Treatment with Acetic Acid.


Nickel

as

sulphate


Volume

of water

solution at

precipitation


Oxalic
acid


Acetic
acid
added


Nickel
found


Error


griu.


cm'


grm.


cm*


grm.


grm.


0-0503


100


2


50


0-0502


-0-0001


00050


100


2


100


0-0054


-f 0-0004


0-0251


100


2


100


0-0258


+ 0-0007


0-0503


50


2


100


0-0514


+ 0-0011


0-0603


100


2


100


00502


-0-0001


0-1257


100


2


100


0-1271


+ 0-0014



Table III. The positive errors may be assigned to two causes,
inclusion of the precipitant and uncertainty of end-point when
titrating in colored solutions.

Determination of Zinc as the Oxalate,

It was found to be possible to estimate zinc volumetrically as
the oxalate by the process already outlined for nickel. In this
case, no colored salts being present in the solution on nitration,
a more definite end point was secured and the results obtained
are much more accurate, as appears in Table IV.







Table IV.




The Determination of Zinc by Precipitation with Oxalic Acid




and Treatment with Acetic Acid.




Zinc


Volume






as


at


Oxalic Acetic Zinc




acetate


precipitation


acid acid found


Error


grm.


cm"


grm. cm' grm.


grm.


0-0055


100


2 100 0-0056


+ 0-0001


0-0274


100


2 100 0-0276


+ 0-0002


0-0548


50


2 50 0-0553


+ 0-0005


0-0548


100


2 100 0-0550


+ 00002


0-1370


100


2 100 0-1372


+ 00002



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388 H, L. Ward — Estimation of Lead^ Nickel^ and Zinc.

The oxalate of zinc obtained by the method of Classen* was
contaminated with potassium oxalate and therefore could not
be used to determine the amount of zinc present. On ignition
and washing of the oxide obtained, it was shown that all the
zinc was recovered.

Summary,

Experiments have been given to show that lead may be
determined by precipitation, either with ammonium oxalate or
oxalic acid, in the presence of large volumes of acetic acid and
titration of the oxalate formed with permanganate.

Nickel has been estimated by precipitation by oxalic acid in
water solution, the addition of acetic acid to separate the metal
remaining in solution, and titration with permanganate.
Errors may occur in this method from inclusion of the pre-
cipitant or indefiniteness of the end point.

Zinc may be estimated very accurately by the method used
for nickel.

* Classen, Zeltschr. anal. Chem. , zvi, 470.



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Case and WUliston — Desci'iption of Reptilian Skulls. 339



Art. XXX. — A Dedcription of the Skulls of Diadectes lentus
and Animasaurus carinatus ; by E. C. Case and S. W.

WiLLISTON.

The two skulls here described have recently come to light.
The first was collected by Case in the Baldwin Bone Bed on
Poleo Creek in Rio Arriba County, New Mexico, and the
second was collected by Baldwin near Animas, Colorado
nearly thirty years a^o, but has lain undescribed among the
abundant material of Yale University. The matrix of the
second skull, an indurated blue clay, is different from any
occurring in the New Mexican localities, but the similarity of
the skull to that of Diadectes and the geographical proximity
indicate that it is a member of the same fauna.

Diadectes lentus Marsh. (Figs. 1 and 2.)

Nothodon lentus Marsh, this Jonrnal. vol. xv, p. 410, 1878.
Nothodon lentus Case. Publication 145, Carnegie Institution, p. 30, 1911.
Nothodon lentus Wiiliston, American Permian Vertebrates, Chicago, p. 16,
1911.

The only portions of the skull of this animal known pre-
viously were the few teeth described by Marsh and the imper-
fect top of a skull described by Wiiliston in the paper cited
above. The history of the discovery and description of the
original specimen lias been given by Wiiliston in the paper
cited above (pages 7 and 8) and need not be repeated. The
uncertainty as to the generic identity of Nothodon and Dia^
dectes has been removed by the discovery of this specimen
associated with typical diadectid vertebrae with hyposphene
and hypantrum in the original Baldwin bone bed.

The skull was found in a matrix of soft, blackish, friable
clay on the banks of Poleo Creek about a mile above its junc-
tion with the Puerco river in Rio Arriba County, New Mex-
ico. Closely associated with the sknll were found the two
jaws described in this paper and they would have been
regarded as belonging to the same specimen if several other
jaws of the same size had not been found with them.

The anterior portion of the skull, as far back as the post-
orbital region, was taken out in plaster and the relation of the
parts can not be questioned. The posterior portion was
broken in the ground and recovered as fragments. As
restored, the skull resembles very closely that of Diadectes in
form and proportions.

The top of the skull is very nigose in the occipital and fron-
tal regions, but on the sides of tlie tempoml and facial regions
the bones are marked by a sculpture of fine pits. The



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340 Case and Williston — Description of JieptUian Skulls.

sutures can not be made out nor can any grooves such as fig-
ured by Williston (Am. Permian Verts., tig. 1 and pi. xxxviii)
be seen. In the specimen figured by Williston the bones
were separated and the sutures thus determined resemble very
closely those shown in the single specimen of Diadecies from
Texas, in which the sutures can be made out. Cope mentions
the occurrence of grooves on tlie skull of Chilonyx^ consider-
ing them to be the marks of attachment of corneous plates,
but these could not be seen by Case. Seeley mentioned the
occurrence of mucous grooves on the skull of PareiasauruSy
but this has been questioned. So far as we are aware, these
are the only mentioned cases of anything resembling the
grooves described by Williston. The only notable differences
from the skull of Diadecies phaseolinits^ the best known, are :

1. There are no pits on the surface of the supraoccipital bone.

2. The pits on the surface of the temporal region are very
obscure and cannot be certainly distinguished from the deep
interspaces of the rugosities.

3. Tliere are small pits on the surface of the prosquamosal
bones just anterior to tlie upper anterior border of the quad-
rate.

4. The jugal descends to the lower edge of the quadrate.
These differences are certainly not of generic value.

The nares are far anterior and in the crushed condition of
the specimen appear to look upward ; this is, however, an exag-
geration of the natural condition, in which the nares were
inclined somewhat inward and forward and looked almost
directly outward. The nasal canal is inclined inward and down-
ward and opens on the sides of the palatines and prevomers
(vomers) at the posterior edge of the premaxillaries, a little
posterior to the anterior opening.

The orbits are elongate oval in outline and inclined slightly
inward at the upper edge.

^\\Q parietal foramen is, as in all the Diadectidae^ 'enor-
mous'. These are the only openings in the skull except the
otic.

The premaxillaries are short and very heavy. Each one
carries four strong incisor teeth (not two as described by Mai-sh)
very prominent and protuberant ; this is most evident in the
median ones; the inclination becomes less in the outer teeth.
The inner surface of the crown is beveled by a flat surface
forming a strong chisel-like cutting edge. The surface of the
crown IS smooth but the roots are marked by deep striations.
An isolated incisor tooth from another specimen has an imper-
fect root 22""" long with the crown IT'S""" long. There can
remain no question of the true thecodonty of the teeth.

The maxillaries have the alveolar portion greatly swollen



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Ca%e and Williston — Description of Reptilimi Skulls, 341

to accommodate the wide sockets for the teeth. The outer por-
tion, forming the sides of the facial region, is thin and marked
with a sculpture of tine pits. The swollen portion departs
abruptly from the inner side, forming a gently swelling promi-
nence ; from a point near the middle of the inner side of this
swollen portion rises the palatine process of the maxillary
which projects from the bone at a fairly steep angle and leaves
a deep groove between it and the bone proper. The process
is thin and the lower edge is slightly rugose. It extends in a
gentle curve, following the outline of the inner edge of the
maxillary, from the tliird or fourth tooth to beyond the last
tooth. The character of this process has been in doubt. Cope
and Case believing that it might possibly be the palatine bone,
but the condition of this specimen leaves no doubt of its true
nature. There are 11 maxillary teeth ; the fii*st has the form
of the incisors except that the face is not so broad and chisel-
like. It is smaller than the incisors and there is no approach
to a canine character. The second is smaller than the first
and more conical in form. Both of these are nearly vertical.
The succeeding teeth, except the last, have the characteristic
transverse widening ; the first of these, the third of the series,
has a sharp median cusp and the inner and outer edges are
rounded ; the rest, except the eleventh, have a median cusp and
lateral cusps on the inner and outer edges, identical with the
teeth of iJiadecies phaseoLinus Cope. The teeth increase in
width to the sixth or seventh and then decrease to the poste-
rior end. The eleventh is not preserved, but the outline of the
base shows it to have been small and conical. Whei;^ first
erupted the enamel of the teeth was marked by rugose lines
which radiate from the central cusp, but these are soon removed
by wear, and in old individuals the surface is nearly flat.
Inhere is a deep pit on the inner side of the base of each of the
teeth, marking tlie position of successional teeth.

T\iQ prevomers (vomers) are paired and articulate strongly
with the premaxillaries in front, the pterygoids behind, and
the palatines laterally. They are of considerable vertical
extent and closely applied to each other in the median line.
Case (Publication 145, Carnegie Institution, p. 71) has described
the posterior ends of the prevomers as spreading apart above
at the posterior end and receiving the lower edge of the eth-
noid. It is now apparent that this open portion is the anterior
end of the pterygoids or the posterior of the palatines. The
lower surface of the prevomers is flat and there is a series of
small, sharp, conical teeth about a millimeter in length. The
posterior limit can not be determined as tlie suture between
the prevomer and the pterygoid is not distinguishable.

T1\\Q palatines are gently convex upward ; the outer edge is



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342 Case and Williston — Description of ReptUidn Skulls.

attached to the maxillaries throughout their length ; there i8
no palatine vacuity. The position of the palatme-pterygoid
suture can not be made out. The anterior portion of the
inner edge of the palatine is applied to the outer surface of
the prevomers, the attachment being by overlap. There are
no teeth on the palatine.

Fig. 1.



Fig. 1. Palate of Diadectes lentus Marsh, x |. Mus. University of

Chicago.

The pterygoids are slightly convex upwards in the anterior
portion ; the inner edges of the two bones meet, if at all, at
the anterior ends, leaving an elongate vacuity which widens
posteriorlj'. It is uncertain whether the anterior ends of the
pterygoids meet or whether the vacuity is closed by the union
of the prevomers (vomers). The edges of the pterygoids form-
ing the sides of the median vacuity are lined with small teeth
and the flat surface of the bone adjacent to the posterior part
of the vacuity is covered with small shagreen-like teeth. The



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Case and WiUiston — Descriptioti of Jieptilian Skulls. 843

middle portion of the pterygoid widens and is slightly concave
on the lower face ; this portion is marked by a Tow line con-
vex anteriorly. On the onter side of the middle of the bone
is the low ectopterygoid process : its outer edge and a portion
of the upper surface is slightly rugose, but there is no approach
to the prominence which the same process gains in jLabido-
saurus and Capto7*hinu8 and there are no teetn on the process.
Near the median vacuity there is slightly prominence on the
inner edge of the bone which curves inward and backward
over the vacuity. The articulation with the basisphenoid is
by strong flat faces. The pterygoids are separate from the
basisphenoids in the specimen, but were found articulated in
position so that the nature of the free articulation is beyond
doubt. Posteriorly the pterygoids send the usual vertical
plates back to join the quadrate.

There is no evidence of an ectopterygoid. This bone has
been in question, but it seems to us there can no longer be
doubt of its absence.

The basisphenoid is represented by the anterior end, only.
There is a small but well developed foramen in the middle
line. The parasphenoid rostrum is strong ; the lower edge is
thick and flat but the upper edge is thin and the whole bone
becomes thin anteriorly ; it terminates freely a little beyond
the point where the median vacuity is closed by the approxi-
mation of the pterygoids or pre vomers. It is apparently this
bone which was figured by Case as the ethmoid in Diadectes
phaseolinus. It is worthy of note that this bone, so stroug in
this specimen, is wanting in many of the described skulls of
Diadectes^ perhaps by accident, and it was originally reported
that it was absent.

Above the parasphenoid process there are the shattered
remains of very thin plates of bone which can not be restored.
It is apparent that they were paired and that they reached up
to the lower surface of the parietal or frontal bones. They
are probably the anterior ends of the sphenoid plates describea
by Case.

The quadrate resembles the same l>one in the specimen of
Diadectes described by Case from Texas (No. 4839 Am. Mus.
Nat. Hist.), but the shaft is a little longer and there is a promi-
nent tuberosity on the posterior surface just above the articular
surface. It is probable that there was such a tuberosity on
the Texas specimen but that it was destroyed by the accidents
of fossilization.

It is necessary here to correct certain errors in the restora-
tion of the sknll of Diadectes published by Broom (Bull. Am.
Mus. Nat. Hist., vol. xxviii, Art. XX, pp. 216-217, figs. 11
and 12). In figure 11, the side view, Broom shows an enlarged
anterior maxillary tooth resembling a canine, a diastema,

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344 CcLse and WiUi%ion — Description of Reptilian Skvlle,

and a decrease in the size of the incisors from within outward.
The character of the incisors is evidently hypothetical as they
are shaded, but the arrangement is wrong as can be made
out from this specimen and from several others in the Ameri-
can Museum. There is no diastema and in no specimen of
Diadectes is there any indication of an enlarged maxillary. It
was upon such an error that Cope founded the genus Empedia^,
In figure 12, the palate, the arrangement of the bones is
wrong. The premaxillaries are never so wide, antero-poste-
riorly, as figured ; the prevomers extend much farther forward
than figured ; the palatine process of the maxillary is figured
as a palatine; the pterygoids are figured as short bones with

Fig. 2.




Fig. 2. Lower jaw of Diadectes lenhis Marsh. ^^2- ^^^* University

of Chicago.

the prevomers extending back as far as the posterior end of
the maxillaries; an ectopterygoid is figured, — as already stated
we find no evidence of such a bone in the Diadectidce. We
have studied the known skulls of />iarf^^^e^5 carefully for several
years and have found no evidence to warrant drawing the
sutures of the temporal region so definitely as Broom has done,
though they may be correct.

The lovjer jaic. — The resemblance to the lower jaw of the
specimens of Viadectea from Texas is very close, but the jaws
from New Mexico show the sutures and permit the outline of
the individual bones to be determined. On the inner side the
suture between the splenial and dentary is distinct in front
but is not traceable beliind ; its probable continuation is indi-
cated by the dots in the figure. Below the anterior Meckelian
opening the suture between the splenial and the surangular is
very distinct. The splenial takes the usual large part in the
symphysis. The suture between the angular and the bone
above it in the po'sterior portion of the jaw is distinct, but it is
somewhat uncertain what this bone is. The articular is not
marked off by distinct sutures, but on the surface of the bridge
between the anterior and posterior openings of the lower



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Case and Williston — Description of Reptilian Skulls. 3i5

jaw there is a low, slightly rugose ridge wliich appears to mark
the portion of a suture which has closed. If this is true, the
portion of the bridge behind the rugose line may be the ante-
rior portion of the articular, and the anterior portion of the
bridge may represent the prearticular ; the ridge may, however,
be only a surface for the attachment of muscles. The coronoid
is a very small bone visible on the inner side of the jaw. The
surangular behind and the dentary in front send processes up-
ward which aid in the formation of the coronoid process. The
sutures on the outer side of the jaw can riot be made out except
where a break in one of the jaws shows that the suture between
the dentary and the surangular runs downward a little anterior
to the coronoid process. The articular face of the articular
has two deep parallel grooves which limited the motion of the
jaw to the vertical plane. There are fifteen teeth in the jaw.
The posterior one is small and conical ; the next eight have the
expanded form characteristic of the genus. The first four have
the chisel-like form of true incisors, the fifth is nearly conical,
the sixth has the crown slightly expanded and carries a single
median tubercle. The other have wide crowns with three
tubercles. The wear was on the outer side of the teeth in the
lower jaw and the inner side in the upper.

Animasaurus carhiattis, gen. et sp. nov. (Fig. 3.)

The specimen consists of a fairly perfect skull (No. 1107
Mus. Yale Univ.). It is slightly injured in the anterior part so
that the premaxillaries, the anterior ends of the maxillaries and
the nares are lost. The anterior portion of the facial region is
crushed down upon the palate. The teeth are all destroyed,
but the outlines of the roots show them to have been trans-
versely expanded as in Diadectes. The condition of the speci-
men is such that the sutures can not be made out and the hard
matrix can not be entirely removed from the palate, but enough
has been taken away, aided by a fortunate break, to make the
structure evident.

2'he superio?* surface of the sTcidL — Due to the position of
the quadrate, the posterior portion of the skull is proportion-
ately much broader than in Diadectes though the occipital por-
tion is narrower: The surface is rougliened by sculpture and the
development of tubercular prominences which recall those of
the genus Chilonyx, This appearance is heightened by the
position of the quadrate, which slants inwards instead of lying
nearly parallel to the lateral surface, narrowing the occipital
region. The parietal foramen is very large, approximately
20'"'" broad by 25'"°^ l^"g- This opening is farther forward
than in Diadectes^ a line drawn through the posterior edges of
the orbits cutting through it at near the center; in Diadectes

Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 196.— April, 1912.
23



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346 Case and WiUistofi — Description of Reptilian Skulls.

such a line passes anterior to the opening. The outlines of the
various bones can not be made out but it is evident that the
frontal was very short and took no part in the superior border
of the orbit.

The lateral aspect of the skull, — Allowiner for the crushed
condition of the anterior end, the lateral profile resembles that
oi Diadectes, The orbits appear to be narrowed vertically, but
this is evidently due to crushing. On the right side there is

Fio. 3.



Fig. 3. Palate of ^»iima«aurtts can naiua Case and Williston. x }^. No.
817, Mu8. Yale University.

a large opening in the temporal region but this is of accidental
origin instead of a true temporal foramen, as is evidenced by the
sharp break of the ed^es and the lack of a corresponding open-
ing on the opposite side.

The palatal aspect of the sTcuU. — This shows the great diflfer-
ence between this genus and Diadectes, The alveolar edges of
the maxillaries are broadened as in Diadectes for the accom-
modation of the widened teeth, but the palatine process of the
maxillary is perhaps different : it appears to rise from the inner
edge of the alveolar surface instead of from the middle of the
inner side of the swolleti portion of the bone and there is no deep
groove between it and the maxillary proper. The pterygoids
and prevomers are united in the median line througliout their



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Case and Williston — Description, of Beptilian Skulls. 347

length, forming a deep median keel ; there is no median vacuity
between the pterygoids but posterior to them there is a deep
vacuity, the circular opening of which looks backwards and
downwards at an angle of nearly 45° to the horizontal axis of
the skull.

T/ie posterior aspect of the skull. — The occipital portion is
narrower than Diadectes owing to the position of the quadrates
and the paroccipitals and exoccipitals are shorter. Tlie artic-
ular face of the quadrate is much narrower than in Diadectes
and the whole bone occupies a very diflferent position with rela-
tion to the basicranium. In Diadectes lentvs the quadrate lies
much farther forward, the articular surface being opposite the
posterior end of the basispbenoid ; in Diadectes phaseolinns
the articular face of tlie quadrate lies opposite the middle of
the same bone, while in Afiimasaurus cai^inatus it lies pos-
terior to the posterior end of the bone. This accounts largely
for the wider appearance of the posterior end of the skull in
the latter.

The individual bones can not all be made out, but such as
can are described below.

The maxiUaries are similar to those of 'Diadectes except as
noted in the description of the palatine process. The posterior
end of the bone is continuous with and on the same level as
the jugal ; in Diadectes it stands out as prominent point. There
are nine bases of teeth and alveoli in the portion of the bone
preserved. The posterior one was small and conical, as indi-



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