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Jacobson's organ with the lateral nasal canal is the open-
ing of the duct of Jacobson's gland, fig. 6, jd^ the
opening being at the inner angle of the organ. The
gland itself, figs. 4 to 8, jV/, lies below the cavum nasale
and lateral nasal canal and is on a level with Jacobson's
organ. Jacobson's gland, as in other Anura, is situated
on the median side of the olfactory organ, and in front it
extends laterally beneath the nasal cavities. It consists
of convoluted cylindrical tubules lined with cubical or
low columnar protoplasm, both nuclei and protoplasm
staining deeply. It extends from a point somewhat in
front of the planes of fig. 4 to that of fig. 8. Its duct
passes from the anterior fourth of the gland to empty
into the organ of Jacobson, Plate V. In fig. 4 there is
a gland, g, which appears diflerentiated from the rest.
It continues forward as a tube, and finally enters into the
lateral nasal canal just posterior to the plane of fig. 2.

Farther forward (figs. 4-7), the lateral nasal canal ex-
pands externally into a secondary cavity, hi, which is
lined with the same sensory epithelium as the cavum
nasale, with which it remains in connection by the nar-
rower and much depressed portion of the lateral nasal
canal. This latter is lined with undiflferentiated low
columnar cells. More anteriorly, the secondary cavity
gradually bends downward and inward so that its anterior
resfion comes to lie below and in the median line of the
rest of the olfactory apparatus as shown in Plate V.

From the anterior end of the lateral nasal canal the
nasal canal continues forward as a flattened tube to the



104 BULLETIN OF THE ESSEX INSTITUTE.

external nares. Its epithelium throughout is of an undif-
ferentiated character.

The cavum nasale is nearly the same size and shape
throughout its whole length (en, figs. 2-9). It is com-
posed of specialized cells, and, in its grosser features, its
histology is similar to that of Jacobson's organ. It has
fine branches of the olfactory nerve- distributed chiefly
to its internal part. These are in many cases too small to
be seen with the magnification used. At its anterior end,
it becomes separated from the lateral nasal canal (fig. 2)
and soon ends as a small blindsac.

In fig. 5, the naso-lachrymal duct is seen. It can be
traced for several sections, but as yet it has not formed
its connection with the cavum nasale, as it apparently
does in a later stage.

It is yet too early too say how much w^eight is to be
placed upon the varying conditions of the olfactory organ
in settling the vexed questions of the interrelationships of
the Amphibia. Too few forms have as yet been studied
to allow of any broader generalizations. Naturally one
would expect to find more points of resemblance between
the conditions occurring in Pipa and in Rana than between
Pipa and the Urodeles, but from the foregoing account it
will be seen that Pipa is about as widely removed in its
nasal structure from the one as from the other. Certainly,
if much weight is to be given these structures, naturalists
are justified in the separation of the Aglossa from the
other Anura.3

In more detail, these diiferences are as follows : —

- Fischer ('43) has figured anrt described the olfactory nerve as double in this
species; his figures representing the two components as arising side by side,
directly from the l)rain. His account has often been quoted. I find, liowever,
that the olfactorius arises by a single root and the nerve passes undivided
through the ethmoidal cartilage, and almost immediately after its emergence
breaks up into two superimposed branches which at once sul)divide for distri-
bution to tlie olfactory epithelium.

» A study of the structures In Dactylethra would prove very interesting.



THE NASAL ORGANS OF PIPA AMERICANA. 105

In Rana esculenta, as described by Seydel, the cuvum
nasale and the nasal canal are not diflferentiated from each
other, and, while the cavum nasale terminates in both in
a cul-de-sac, this termination in Rana is in front of the
external nares, in Pipa behind it. Then, too, the lateral
nasal canal of Pipa is a structure differing considerably
from that of Rana both in position and in histological
differentiation. In Rana, Jacobson's organ lies beneath
the main nasal canal (cavum nasale) and extends inwards
as far as does any other structure connected with the
olfactory region. In Pipa, on the other hand, it is not
covered by any of the other nasal structures, and it is
placed entirely on the external side of the whole nasal
apparatus. From the whole course of the duct, so far as
developed, the naso-lachrymal canal in Pipa will appar-
ently connect with the cavum nasale, while in Rana it
opens into the lateral nasal canal. The most posterior
blindsac, given off behind Jacobson's organ, is apparently
unrepresented in other Amphibians so far as I have
studied the literature. Its lack of specialized sensory
epithelium would seem to imply that it was of no great
importance.

It seems uimecessary to make any comparisons with the
Urodeles farther than to point out that in some respects
Pipa seems to be intermediate between these and the
Anura, especially in the relationships of what I have
called the nasal canal, which agrees well in some respects
Avith what Seydel calls the respiratory duct. Again the
position of Jacobson's organ is nearer that found in Uro-
deles than that occurring in Rana and Pelobates.

Comparisons with the account given by Born ('77)
of the conditions found in Pelobates show differences as
great as those occurring between Pipa and Rana. One
thing that is necessary in these studies is a new nomen-
clature of the parts. The terminology employed by



106 BULLETIN or THE ESSEX INSTITUTE.

Born and by Seydel is hardly applicable to Pipa. I have,
however, refrained from proposing any new names since
I believe that this can only be done in a satisfactory man-
ner by one who is making a comparative stndy of many
different forms, and not by one who has only the limited
perspective of a single species. Still it is well to point
out what terms are employed by Born for the nomencla-
ture adopted here which is based upon the terminolog}'^ of
Se3'del.

Born distinguished three blindsacs which lie directly
under each other ; the upper being the largest and the
middle the smallest. Born's "unterer Blindsac " may be
compared to the Jacobson's organ in Pipa, while the
"oberer Blindsac" is the cavum nasale. Born also finds
another blindsac between the other two, which may possi-
bly be compared to a similarly lying unnamed blindsac
which Seydel found, the "a" of his figures, and possibly
to the enlargement of the lateral nasal canal in Pipa. It
is true that in Pipa it forms no blindsac, but it is special-
ized and forms an enlargement which, from the outside,
might readily he taken for an actual blindsac. This
enlargement is situated between the Jacobson's organ and
the cavum nasale in Pipa, but is more internal in Rana.

[Published, lAlarch, 1897.]



THE NASAL ORGANS OF PIPA AMERICANA. 107



LITERATURE.

'94, Arnold, G. A. The anterior cranial nerves of Pipa americana.
Tufts College Studies, No. 1.

'84, Blaue, J. Untersuchungen iiber den Bau der Nasenschleimhaut
bei Fischen und Amphibieu. Arch. Anat. u. Phys., Anat. Abth., 1884.

'77, Born, G. tjber die Nasenhohle und den Tliranennasengang der
Amphibien. Morph. Jalirbuch, ii, 1870.

'43, Fischer, J. G. Amphibiorum nudorum neurologiiB specimen
primum. Berlin, 1843.

'93, Lee, Stewart. Zur Kenntniss der Olfactorius. Berichte Na-
turf. Gesellsch. Freiburg i. B., vii, 1873.

'95, Seydel, O. Lber die Nasenhohle und das Jacobson'sche Organ
der Amphibien. Morph. Jahrbuch, xxiii.

EXPLANATION OF PLATES.

Plate IV. Nine consecutive sections of the nasal region, fig. 1 being
a short distance behind the external narial opening, fig. 9 passing
through the internal nares.

Plate V. A, Dorsal, and B, Ventral veins of a reconstruction of
the nasal apparatus of Pijxi americana. In B is shown in outline the
limits of the internal cavity ; while in both figures the planes of the
sections shown in Plate IV are indicated.

ABBREVIATIONS.

:Jacobson's organ.
: lateral nasal canal.
: nasal canal.
: branch of nasalis.
olfactory nerve.
: cavum nasale.

: external portion of the nasal canal.
: Jacobson's gland.
: Jacobson's duct.
: posterior blindsac.
: difl'erentiated gland.
:naso-lachrymal duct.
= branch of olfactory nerve to Jacobson's organ.



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SUPPLEMENTARY REPORT

ON THE MINERALOGY AND GEOLOGY

OF ESSEX COUNTY.



BY JOHN H. SEARS,
Curator of Mineralogy and Geology, Peabody Academy of Science.



During the seasons of 1894, '95 and '96, the principal
work in the geology of the county has been the study of the
quartzite and interstratitied beds in Lynnfield Centre and
North Saugus and carrying the work southwest into Mid-
dlesex County in the towns of Reading, Wakefield, etc.
The quartzite beds of North Saugus are, without doubt,
parts of the basal Lower Cambrian and the knowledge of
this formation has been extended southeast on both sides
of the head waters of Penny l)rook to Saugus river. The
quartzite and inters tratified slates and coarse conglomer-
ates of Lynnfield Centre are the basal members of the
Carboniferous rocks, a continuance of the blocked area,
No. 19 on the map, of Topsfield and Middleton. This
work makes several changes necessary in the preliminary
map published in 1893. As an evident mistake was made
in the mapping of the contact of the hornblende-granite
and the diorite areas of Marblehead and Swampscott,
these have been more carefully worked out and remapped.
Another correction made necessary is the separation of
the hornblende-granites from the hornl)lende-biotite-
granitite. This was not done when the map was published

ESSEX I>'ST. BULLETIN, VOL XXVII 11* (109)



110 BULLETIN OF THE ESSEX INSTITUTE.

on advice at the time, although I personally felt then that
it would have been better to do so. Another correction
is an addition to the augite-nepheline-syenite area. The
augite-nepheline-syenite area in Gloucester and Rockport
has been extended over two miles and remapped on the
west side of Cape Pond. This work was greatly assisted
by the Gloucester and Rockport street railroad work and
the trenches opened by the Rockport water works, when
numerous sections of the fresh rock were exposed thus
aflbrding good specimens of the rock for investigation.
Many specimens from these outcrops have been collected
and the data thus at our disposal have been of great help
in tracing this rock formation. The trend of the auojite-
nepheline-syenite rock from Gloucester to these outcrops
in Rockport and to Sandy bay and the Dry Salvages is in
the usual northeast direction and unites in this area the
augite-nepheline-syenite, the so-called black granite of
the Rockport Granite Company's Quarry. Having thus
traced the augite-nepheline-syenite in comparatively nar-
row area, through the hornblende-biotite-sfranitite rock-
mass, it is an indication that the syenite is the younger
rock and cuts through thegranitite without these recently
seen outcrops; and, with the knowledge at our command
when the geological map of Essex County was published,
the small detached areas of the augite-syenite in this
region seemed to be cut by the granitite, thus making the
granitite apparently the younger rock. I have therefore,
taken all of the maps remaining on hand at the Essex
Institute and have made the necessary corrections to date
in color.

These corrections may not appear important to the un-
trained eye ; still they are so to the student and it at least
brings the maps on hand correct to our best knowledge to
the present time.



SEARS'S SUPPLEMENTARY REPORT. lH

Revised scheme of numbers.

(-(-) Hornblende gr.-mite.

(12) Eruptive porphyritic gneiss.

(18) Cambrian rocks.

(19) Carboniferous rocks.



GEOLOGICAL SUCCESSION OF THK KOCK FORMATIONS OF

ESSEX COUNTY, MASS., FROM THE EARLIEST TO

THE MOST RECENT.

Archean, Laurentian gneiss, schists and sandstones, all
crystalline, more or less contorted and highly metamorphic.

Pre-Cambrian, Arkoses, Hornblende epidote gneiss,
Limestones, folded and metamorphic.

Lower Cambrian (Paleozoic) conglomerates, quartzites,
slate and limestone, Georgian Olenellus, etc.

Eruptive (igneous) rocks, muscovite biotite granite.

Hornblende granite.

Hornblende biotite granitite.

Eruptive porph3ritic gneiss.

Quartz augite diorite.

Quartz hornblende diorite.

Essexite nepheline rock and aegirite ditroite schieffer.

H(»rn])lende diorite.

Elaeolite zircon syenite and augite nepheline syenite.

Hypersthene augite basalt dyke rocks (eobasalt).

Augite olivine basalt dyke rocks.

Diallage gabbro dyke rocks.

Diallage augite olivine gabbro dyke rocks.

Aegirine Tinguaite d3'ke rocks.

Aegirine syenite dyke rocks.

Ancient volcanic rocks, rhyolite breccias, banded
rhyolite, corhyolite.

Hornblende diorite dyke rocks.



112 BULLETIN OF THE ESSEX INSTITUTE.

Hornblende augite porphyrite, feldspars from one to
three inches long, dyke rock.

Aphanitic diorite dyke rocks.

Aplitic granite dyke rocks.

Felsite porphyry dyke rocks (eorhyolite).

Bostonite porphyry (sanadindyke rock).

Quartz porphyry dyke rocks (eorhyolite).

Liperite dyke rock (eorhyolite).

Vitrophyre dyke rock (eorhyolite).

Keratophyre lava (anorthoclase rock), a sheet covering
the rhyolite breccia and banded rhyolites on Marblehead
Neck.

Paleozoic Era, Carboniferous Period, Permo-Carbon-
iferous Epoch. Very coarse ferrugiueous conglomerates
and grits, blue shales, sandstones and black limestone,
that is fossiliferous.

Surface deposits.

Cenozoic Era, Pleistocene Period, Pre-glacial Epoch.
Pre-glacial clay beds, covered by glacial boulder till (older
diluvium) occurring in long ridges or drums, which lie in
the general direction of the rock striations.

Cenozoic Era, Pleistocene Period, Glacial Epoch.
Scratched, grooved, polished and striated surfaces of
ledges and stones, drift boulder clays. Terminal moraines
as drums and drumlins. Eskers, valley sands and clays
deposited in ice dammed seas. This determination may
include inter-glacial epochs and a post-glacial epoch.

Psychozoic Era, Post-Terrace period. Present Epoch.
Peat-beds, river alluvium. Evidence of subsidence, sub-
merged forest trees, cones, nuts and fruits ; also many
hundreds of wino;s and fragments of beetles and other
insects submerged to a depth of fourteen and one-half feet
below high water mark. For full description, see Bul-
letin of the Essex Institute, Vol. xxvi, 1894.

Peaboi>v Academy of Science,
Salem, Marcli 29, 1S97.



SANDSTONE DIKES

ACCOMPANYING THE GREAT FAULT

OF UTE PASS, COLORADO.



BY W. O. CROSBY



introduction-
Three years aijo, Whitman Cross' first directed the
attention of geoloffists to the fact that dike-like masses
of sandstone occur in the granite of the Pike's Peak
massif, formino^ a belt aliout one mile wide extending
north-northwest from the vicinity of Green Mountain
Falls, in Ute Pass, along the southwest side of the
narrow Manitou Park l)asin of sedimentary rocks (Silu-
rian and Carboniferous). Among the most important
characteristics of the dikes noted by Cross are the fol-
lowing : —

L The dikes have a general trend parallel to the l)elt
in which they occur ; are approximately vertical and
often appear as a complex of nearly parallel fissures with
many In-anches and connecting arms ; and vary in width
from mere tilms to two or three hundred yards, the
largest being a mile or more in length, and forming
ruffffed ridsres with narrow crests which contrast mark-
edly with the gently sloping hills of granite alwut them.
In short, ''in all formal relationships to the enclosing

' Bull. Geol. Soc. Aincrica, .'>, 225-2;;0;
U. S. Geol. Survev, I'ike's Teak Folio.

(113)



114 BULLETIN OF THE ESSEX INSTITUTE.

rocks these bodies are as typical dikes as any of igneous
origin. "

2. The rock of the dikes is a fine and even-grained
aggregate of sand grains varying in degree of indura-
tion from a normal sandstone to a dense hard quartzite,
but throughout of a remarkably massive and uniform
character. The induration is mainly due to limonite ; in
the quartzitic portions, however, there appears to be
some secondary silica, although a distinct enlargement of
the quartz grains is rare.

During the past summer of 1896 I was able to devote
several weeks to the investigation of the sandstone dikes
and the great displacement to which I have found them to
be genetically related. To the dikes described by Cross
I gave only sufficient attention to become familiar with
their characteristics ; and then endeavored to trace the
series southeastward through Ute Pass to Manitou and
beyond.

The sedimentary formations of the Manitou area em-
brace, from below upward, as described by Hayden,
Cross, and others :

1. A basal sandstone which is usually forty to fifty
feet thick, white or gray for the lower ten to fifteen feet
and dull red or brown above, only rarely of arkose
character, l)ut frequently move or less glauconitic.
2. This sandstone, which may be referred provisionally
to the Potsdam, becomes calcareous upward, passing into
red, cherty limestones, and these into a massive gray
limestone having a thickness of several hundred feet.
The limestones are throughout more or less magnesia n
and contain recognizable traces of a Lower Silurian
(Ordovician) fauna. 3. This great Manitou limestone
series is overlain without apparent unconformity by the
Fountain (Carboniferous) beds, one thousand to possibly



114 BULLETIN OF THE ESSEX INSTITUTE.

rocks these bodies are as typical dikes as any of igneous
origin. "

2. The rock of the dikes is a fine and even-grained
aggregate of sand grains varying in degree of indura-
tion from a normal sandstone to a dense hard quartzite,
but throughout of a remarkably massive and uniform
character. The induration is mainly due to limonite ; in
the quartzitic portions, however, there appears to be
some secondary silica, although a distinct enlargement of
the quartz grains is rare.

During the past summer of 1896 I was able to devote
several weeks to the investigation of the sandstone dikes
and the great displacement to which I have found them to
be genetically related. To the dikes described by Cross
I gave only sufficient attention to become familiar with
their characteristics ; and then endeavored to trace the
series southeastward through Ute Pass to Manitou and
beyond.

The sedimentary formations of the Manitou area em-
brace, from below upward, as described by Hayden,
Cross, and others :

1. A basal sandstone which is usually forty to fifty
feet thick, white or gray for the lower ten to fifteen feet
and dull red or brown above, only rarely of arkose
character, l)ut frequently more or less glauconitic.
2. This sandstone, which may be referred provisionally
to the Potsdam, becomes calcareous upward, passing into
red, cherty limestones, and these into a massive gray
limestone having a thickness of several hundred feet.
The limestones are throughout more or less magnesian
and contain recognizable traces of a Lower Silurian
(Ordovician) fauna. 3. This great Manitou limestone
series is overlain without apparent unconformity by the
Fountain (Carboniferous) beds, one thousand to possibly



SANDSTONE DIKES OF UTE PASS. 115

fifteen hundred feet in thickness — a remarkable complex
.of red and white arkose sandstones, grits and conglom-
erates. 4. The red sandstone series (Triassic), a
thousand feet or more in thickness. 5. The white,
variegated and gypsiferous Jurassic strata. 6. The
Cretaceous series, l)eginning with the massive and con-
spicuous Dakota sandstone.

Each of these formations is cut off on the south by
the great fault which skirts the northeastern base of the
Pike's Peak massif. This profound displacement, which
must be regarded as a dominant factor in the oreological
structure of the region, and to which we undoubtedly
owe, in the main, the Manitou embayment of sedimentary
rocks and the exceptional elevation of the Pike's Peak
massif as compared with the Front Range to the North
of Ute Pass, gained early recognition and is clearly
indicated on Hayden's map of the Manitou area-, the
principal features of which are reproduced in the map
accompanying this paper. Although the traveler through
Ute Pass now leaves the sedimentary rocks and passes
onto the granite within two miles of Manitou, there is,
apparently, no reason to doul)t that the sedimentaries
were once continuous with those of the Manitou Park
area, which now begin a mile north of Green Mountain
Falls or nine miles from Manitou, and coincidentally with
the sandstone dikes described by Cross ; and it is alto-
gether prol)able that the fault by which Cross has
l)Ounded the Manitou Park sediments (Potsdam, Man-
itou limestone and Fountain series) on the southwest
is a direct continuation of that which, cutting across the
strike of the beds, is so much more conspicuous in the
Manitou area. This great displacement, which divides

' Ann. Rep. U. S. Geol. and Geog. Survey, 1874, p. 40.



116 BULLETIN OF THE ESSEX INSTITUTE.

very obliquely the entire Front Range and the beds
lying upon either flank of the range and sloping away
from its crest, may therefore be appropriately designated
the Ute Fault. Erosion has cut deeply enough over the
top of the arch to remove the sedimentary rocks from
the downthrow as well as the upthrow side of the fault.
The Ute Fault cuts everj^ formation of the region from
the fundamental granite and the Potsdam to the Laramie,
and in its maximum throw must exceed the aggregate
thickness of the Paleozoic and Mesozoic terranes ; and its
completion, at least, must date from relatively late geo-
logical times.

SANDSTONE DIKES NORTHWRST OF MANITOU.

The contact of the granite and sedimentary rocks is
obscurely exposed in the southeast bank of Ruxton
Creek, beneath the bridge of the Colorado Midland Rail-
road. It is exposed again and more satisfactorily in the
cut on the railroad at Iron Spring Station (Map, 5). The
cut and the hillside just above it show the Potsdam beds in
normal succession — white sandstone, red sandstone with
glauconitic layers, and red calcareous strata passing into
the normal Manitou limestone. Near the granite the
beds are tilted l)y the drag of the great fault to a dip of
90° Avhich rapidly suljsides to a northeast dip of a1>out
45° degrees at the northeast end of the section. The
actual contact can be located within a foot or two ; and
along this line both the granite and sedimentary rock
are much crushed, the bedding of the sandstone is almost
obliterated, and all the indications suggest a fault.

Within two hundred feet southwest of the fault the
granite incloses several sandstone dikes. One of these
is exposed in the railroad cutting a])Out forty feet from
the fault and the l)ase of the Potsdam. It is fifteen feet



SANDSTONE DIKES OF UTE PASS. 117

thick and hades southwest. An uncertain thickness of
granite separates this from a dike fifty and possibly one
hundred feet wide of undetermined hade. Both dikes
are entirely typical in lithological character, 1)ut in con-
sequence of the deep disintegration of the granite they
are not well exposed. The sandstone is the usual dull
red, blotched and spotted with white where the iron
oxide has been reduced and leached out ; and it seems
to be somewhat glauconitic.

From this point a gulch extends northwesterly along
the line of the old South Park trail, l)etween the long
slope of disintegrated granite and the al^rupt, sharp-
crested hill of the Potsdam sandstone and Manitou
limestone, which still maintain a high northeast dip.
The indications are that the first dike mentioned follows
the bottom of the gulch and the fault-line closely. On
the col at the head of the gulch several irregular dikes of
sandstone, with a maximum width of at least forty feet,
outcrop obscurely in the granite ; and immediately above
on the northeast are the highly inclined Potsdam sand-
stone and red and gray cheily limestones, the lines of
snow-white chert in the lower limestone contrasting


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