British Museum (Natural History). Dept. of Zoology.

Catalogue of the British species of pisidium (recent & fossil) in the collections of the British Museum (Natural History), with notes on those of western Europe online

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Online LibraryBritish Museum (Natural History). Dept. of ZoologyCatalogue of the British species of pisidium (recent & fossil) in the collections of the British Museum (Natural History), with notes on those of western Europe → online text (page 1 of 17)
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B. B. WOODWARD, F.L.S., &c. [BOOL. L






DULAU & Co., LTD., 37 8OHO SQUARE, W. ;




[AH riyltts reserved^}




THE present volume is based on the studies made by the author
in his private time during nine winter sessions. It deals with
the collections of recent and fossil shells, belonging to the genus
Pisidiuntj in the British Museum (Natural History). It is, how-
ever, by no means restricted to these, since Mr. B. B. Woodward
has had the advantage of making use of a large number of
specimens derived from other sources. This is indicated by the
unusually long list of helpers whose assistance he acknowledges
in his Introduction, and to whom the thanks of the Trustees
are also due.

The difficulty of the work has been increased by the small size
of the shells described.

The Catalogue is in one respect a departure from the usual
practice of the Museum, since it deals with the collections of two
Departments, represented respectively by the recent and by the
fossil forms.


Keeper of Zoology.
British Mueeum (Natural History),
London, S.W.
March 7, 1913.









1. Pisidium amnicum (Miiller) 16

2. astartoides, Sandb 27

.'>. casertanum (Poll) 31

4. nitidum, Jenyns 44

5. personatiim. Malm 53

6. pusittum (Gmelin) Jenyns 60

7. ,, inilium, Held 70

8. pulchellum, Jenyns 78

'>. ,, ntbtnatcatum, Malm 84

10. hemlmoanum (Shepp.) , 93

11. supinum, A. Schmidt ,100

12. ,, parvulum, Clessin 105

13. steenbuchii (Miiller) . 107

14. lilljeborgii, Clessin , ... Ill

15. hibernicum, Westld 116

16. obtusale (Lam. ?) Jenyns 119

17. vincentianum, B. B. \Voodw 127







Of all the genera of British non-marine Mollusca none has
presented more difficulties to the student than Pisidium. The
small size of the shells, their great variability, the lack in most
cases of any striking external characteristics, as well as the con-
fusion in which the subject has been left by the various authorities,
have all contributed to these difficulties, with the result that the
genus has been largely neglected.

Very early in our joint work on the post-tertiary Mollusca,
Mr. A. S. Kennard and I were led to see that the group must bo
dealt with, whilst the late Dr. 0. Bottger had urged me to study
it more closely. It was not, however, till Dr. A. C. Johansen
visited this country in 1901 that any serious start was made.
Dr. Johansen it was who directed my attention to the hinge-
characters as the only sure means of identification of the species,
and by his intimate knowledge of the Scandinavian forms he was
able to point out that we had species present in Britain hitherto

The investigation of the British species of Pisidium was to have
been our joint task, but unfortunately for Malacology, Dr. Johansen
on his return to Copenhagen was drafted to other zoological
work, and this attempt to unravel a very tangled skein was left
to me.


Owing to the kind assistance of friends a very large amount of
material has passed through my hands. Among others, I am
peculiarly indebted to my colleagues at the Natural History
Museum, Mr. E. A. Smith, I.S.O., of the Zoological Department,
and Dr. Smith Woodward and Mr. Bullen Newton of the Geological
Department ; to Dr. Kitchin of the Museum of Practical Geology ;
Dr. Scharff of the National Museum, Ireland ; Dr. S. F. Harmer,
then in charge of the collections at Cambridge ; Mr. James Reeve
of the Norwich Castle Museum ; and the Curator of the Concho-
logical Society of Great Britain ; who all freely allowed me to
work over the valuable collections in their charge. Whilst, when
early in the work it became necessary to visit Bath in order to see
Jenyns' types, Mr. F. Shum, the President, and Mr. E. C. Davey,
the Hon. Sec. of the Bath Royal Literary and Scientific Institution,
were most kind and assiduous in affording me every assistance in
my researches.

Among private collectors, besides Mr. A. S. Kennarcl and
Dr. Johansen, thanks are more especially due and are hereby
tendered to :

Dr. R. Bellini (for Italian specimens, including some from the
historic spring at Caserta), the late Dr. 0. Bottger, the late Rev.
R. Ashington Bullen, C. S. Carter, Major M. Connolly, J. E. Cooper,
Capt. W. J. Farrer, Dr. L. Germain of the Museum d'Histoire
Naturelle, Paris (for specimens from the Locard collection), J. W.
Jackson, Dr. F. F. Laidlaw, Dr. K. Lampert of the K. Naturalien-
saoimlung in Stuttgart, W. A. Lindholm of Moscow (for specimens
from Russia and from Lake Baikal), Mrs. Longstaff, H. Lynge (for
Scandinavian specimens), A. Mayfield, J. N. Milne, 11 Marchese di
Monterosato, C. H. Moore, H. C. Napier, Dr. Nils Hj. Odhner (for
Scandinavian specimens), C. Oldham, H. Overton, R. A. Phillips,
H. B. Preston, F. W. Reader (for kind and assiduous assistance in
the preparation of the photographs that form the basis of the plates),
Mons. A. Rutot of the Muse'e d'Histoire Naturelle, Brussels,
A. W. Stelfox, F. H. Sikes, E. R. Sykes, F. Taylor, Dr. J. H.
Theel of the Naturhistoriska Riksmuseum, Stockholm, J. R. Le B.
Tomlin, the late Major H. Trevelyan (who specially dredged some



of the Irish Lakes), Mons. E. Vincent (for Belgian fossil examples),
W. M. Webb, and C. E. Wright. Whilst the Zoological Museum
of Copenhagen furnished specimens of P. steenbucJiii (Moll.).

In the lists of distribution the following abbreviations have been
employed for the names of these and other friends and helpers :

A.M. = A. Mayfield.
A. S. K. = A. S. Keunard.

F.T.=F. Taylor.
H C.N.-H. C Napier.

A.W. S. = A. W. Stelfox.
B. B. W. = B. B. Woodward.
B.M.=I British Museum
(Natural History).
C. C. S. Census of the Concho-
logical Society of

II. 0. = H. Overton.
II. T. = Major H. Trevelyan.
J.E.C. = J. E. Cooper.
J. L. = Mrs. J. Longstnff.
J.N.M. = J. N.Milne.
J W. J.-J. W. Jacksou.

Great Britain."
C.E.W. = C. E. Wright.
C. E. Y. K. = Rev. C. E.Y.Kendall.
. C.H. M. = C. H. Moore.
C.O. = C. Oldham.
C. S. = Conchological
Society's collection.

C. S. C.-C. S. Carter.

K.TI.J.= Statf-Surg. K. H.
Jones, R.N.
M. P. G. = Museum of Practical
N. 1C. = Norwich Museum.
R.A.P. = R. A. Phillips.
S. M. C. = Sedgwick Museum,

fl !1 111 \\ 1*1 f\ IT A

Camb. = MacAndrew collec-
tion, Cambridge.
D. M.=National Museum,
E. C. = E. Collier.
E.R. S.=E. R. Sykes.
F.F.L. = Dr. F. F. Laidlaw.

V^ciill I M 1 1 1 _ .

T.R. = the late T. Rogers
[whose Pisidia are
now in the writer's
W. J. F. = Capt. W. J. Farrer.
W.M. W.=W. M. Webb.





The genus was established in 1821 by C. Pfeiffer (134), who
separated it from Cyclas (i. e. Sjpkaarium) on good anatomical
grounds, namely, as he puts it, that there is a single siphonal tube
at the anterior end of the shell. He was obviously unprepared to
find in this genus the departure from the normal state of the
pelecypod shell whereby the posterior portion is the shorter.

Prior to PfeifFer's time forms now referred to his genus were
placed in Tellina^y Miillcrand others following him, in Splicerium,
by Scopoli, in Card turn, by Poli, and in Cyclas, by Draparnaud,
Lamarck and his school.

In 1818 Ferussac, the elder, in an article on " Cyclade" (61),
subdivided the genus Cyclas and proposed for one of the sections
thus formed the subgeneric name of Corneocyclas, which he stated
was equivalent to the genus Cornea of Megerle (=Sphcerium) (112),
but among the species he cited, following the practice of Draparnaud,
were Cyclas fontinalis, Drap., C. dubia, Say, and " C. amnia,
tellina amnia, Mull." Corneocyclas does not appear to have been
adopted by his cotemporaries, nor does De Blainville allude to it
in his " Manuel de Malacologie " (1825-27) ; he merely gives as
subdivisions of Cyclas: Cornea and Pisum, Megerle.

Dr. Dall (49) has recently sought to revive the name Corneo-
cyclas for Pisidium on the ground that if one removes all the
species included in that subgenus by Ferussac but now referred to
the prior Sphazrium, some species remain that ought to retain the
name Corneocyclas. Seeing, however, that the name was only a
subgeneric or sectional one, established openly as a synonym for a
prior one (Cornea), and that it was never adopted by others, whilst


Dall selects the unknown Tellina pusiUa, Gmelin, as the type,
instead of any of the forms included by Ferussac, one can only
regret that, doubtless with the best intentions, the distinguished
American Conchologist should have further complicated zoological
nomenclature by endeavouring to resuscitate such a mere tentative
sectional designation. To set aside Pfeiffer's name, deliberately
chosen to designate a group of species having a good common
character, in favour of a subgeneric term, that can only be retained
for certain of its incidental members by a somewhat arbitrary
manipulation, is to stretch the much abused law of priority to its
breaking point, and in this Catalogue, therefore, Pfeiffer's name
Pisidium will be adhered to.

In 1820 Rafinesque (146) used Pliymesoda* for one of his
divisions of the genus Cydas, his types being " C. lacustris
(f=.SpJicerium\ C. dubia, Say, &c." Dall, in spite of its mixed
character and faulty definition, revives the name for a section of
his Corneocyclas, taking however as type, Tellina virginica, Gmelin
(p. 3236, no. 39), which is held to have priority over Say's
C. dubia t though what Gmelin's species really was is more than

The synonymy of the genus is :

Pisidium. C. Pfeiffer, Naturg. Deutsch., Moll. Abtlil. i, 1821, pp. 17

& 1237 -
Pisum, "Megerle, 1811 ; non Linn." : Gray, Proc. Zool. Soc. Lond.

xv, 1847, p. 184.
Galileia, O. G. Costa, Fauna Sicilia, Mollusclii, p. 1, pi. i, fig. 2 a,

A, B (1840).

Pern* 8 "' Leach, Syn. Moll. Gt. Brit. 1852, pp. 291-2.

Musculium. Link : II. & A. Adams, Gen. Recent Moll, ii, 1858,
p. 451 (non Link).

With regard to Galihia, 0. G. Costa (sometimes misquoted as
"Da Costa"), the usual reference is to Costa's " Corresponden/a
Zoologica, 1839" (page never given); the name occurs there
(p. 181) as applied to a freshwater bivalve, in a review of the
author's "Fauna Sicilia," &c., 1840 (46), to which the reader
is referred for details. The latter work few appear to have
seen ; in it thegenus and species (Galihia tenebrosa) are described
and apparently excellent enlarged figures given, which would lead
one to suppose the shell was really marine. The Marquess de
Monterosato, however, assures me that these figures are quite
fallacious, and most kindly forwarded specimens from the type
localitv, which is inland. These and other specimens which I
received from Prof. Bellini proved to be undoubted Pisidium
casertanum, very dwarfed and stunted, accompanied in one of the
gatherings by still more stunted P. personatum.

* Misquoted by Prime in his works as " Physemoda."


Pfeiffer's diagnosis of the genus Pisidivm is as follows (134,
Abt. i, pp. 17 & 123) :

* ; PISIDIUM, Nobis.

" Thier : statt der rohrenformigen Tracheen ein schmaler
fleischiger Vorstoss an dem vorderen, Theile der Schaien ;
der Fuss lang und schmal.

" Gehiius : langlich, ungleiehseitig, voilig schliessend ; an dor
rechten Schale ein, an der liuken Schale zwei gegeneinander
iiberstehende, sehr kleine Hauptzahne ; nach hinten und
vorne zwei diinne, lamelleiiformige Seitenziihne; letztere an
der rechten Schale gespalten, um die gegen iiberstehende n

The shell -characters may be more narrowly defined as follows :
Shell close, ovoid to orbicular, equivalve, inequilateral, posterior
side the shorter, more or less concentrically striate, thin, with
olive-horny periostracum, sometimes, especially in young individuals
and certain species, sparsely covered with short hairs ; umbones
sometimes prominent, sometimes tumidly obtuse, nepionic shell
usually smooth ; ligament subexternal ; hinge formula* :

R.V, a. i : a. in
L.V. : a. n :



Fig. 1. Topography of the hinge of Pisidium: B.V. Right valve; L.V. Left
valve ; a.i-ni, anterior lateral teeth ; c.2~4, cardinal teeth ; I, ligament ;
p.i-iij, posterior lateral teeth.

* Felix Bernard's nomenclature for the hinge (14) has been followed as
being the most scientific. R.V. = Right Valve ; L.V. = Left Valve; a=anterior
lateral teeth; <?=cardinal teeth ; /ligament ; and p= posterior lateral teeth.

Bernard points out that the hinge in the Eulamellibranchia arises in the
form of folds parallel with the shell-margin. With growth, deposits of shelly
matter at certain points eventuate in the formation of the teeth of the adult
shell. In the group to which Pisidium belongs, in the right valve c.3 is at
first continuous with a. in, and in the left valve, c. 2 with a. //, c. 4 with a subse-
quently suppressed a.iv. In the species of Pisidium subsequently described
in this Catalogue, it will be noted that all except P. amnicum and P. astartoide*
show traces of the former continuity between c.2 and a.n.


In common with most freshwater mollusca the various species
of Pisidium are extremely susceptible to the influences of their
environment, and thus vary greatly in their external appearance
according to their habitat.

If instead of confining one's attention to the study of rows of
cabinet specimens from various localities, each too frequently
consisting of only some three specimens, the mixed gatherings of
species from different places be taken, it speedily becomes evident
how great is this effect of environment. In one locality, all the
species will exhibit less sculpturing than the normal forms ; in
another, more ; all may be dwarfed, or all abnormally large ;
occasionally one species in the gathering will show greater increase
in size over the average, while its associates are undersized ; or
exaggerated inilation may be the prevailing feature. Thickening,
or attenuation of the shell, or abnormalities, may likewise prove
characteristic of certain localities.

As Jeffreys remarks (and similar observations were made by
Jenyns and others): "Size, substance, sculpture, and lustre are
not of much account, as they mainly depend on the chemical
ingredients of the water inhabited by these mollusks, as well as on
their supply of food" (81, vol. i, p. 18).

In the course of the present investigations it was found that
each species varied in outline from what came to impress itself as
the normal form, towards a more rounded shape on the one hand
and a more elongate on the other, as well as to assume sometimes
a more swollen, sometimes a more flattened condition ; whilst the
hinges of those taken in quiet waters are feeble and weak, in
comparison with the hinges of those habitually dwelling in running

Often, while it is comparatively easy to separate the individual
species in a given gathering (A, B, and C from locality X, or
locality Y), it is a matter of trouble to discriminate between
samples of different species from diverse localities (B from locality
X may be more like C from locality Y, and so on), if only the
external characteristics he depended on. When, moreover, col-
lections from the numerous post-tertiary deposits are examined,
the difficulty is enhanced, for then, swept together by the flood-
waters in which the deposits were formed, one meets with the
mixed rejectamenta of a wide area, where varying environments
abounded, whilst the amount of wear and tear the specimens have
frequently undergone does not render the task of their identification
any the more easy.

The question arises, what then are the best characters to rely
on in distinguishing the species. Jeffreys (81, vol. i, p. 18)
recognized that little reliance could be placed on the soft parts
or at all events on their external features. Nor would these avail
in the present investigations in which it is sought to deal equally
with fossil forms. The external form of the shell, on which
Jeffreys somewhat reluctantly depended, we have seen to be
unreliable. Fortunately the Pelecypod shell far more closely

SPECIES OF risiniUM. 5

reflects the animal than does the Gastropod, and the muscle-scars
in some cases, though not, seemingly, in Pisidium, and especially
the hinge furnish reliable data.

Bourguignat was, we believe, the first to insist on the utility of
the hinge for broadly classifying the species of Pisidium (21, p. 82),
but unfortunately he did not realise the applicability of its detailed
characteristics for the purpose of the determination of species.

Jeffreys, who was acquainted with Bourguignat's paper, over-
looked, or did not give sufficient heed to, the pregnant suggestion,
and it was Olessin (35) who first, in theory at all events, made
use of the detailed hinge -characters for the determination of

Under the circumstances, when entering upon the researches of
which the results are set forth in the following pages, it seemed
advisable to ignore in the first instance all names whatsoever, to
ascertain simply how man}' distinct forms of the genus could be
differentiated, taking the details of the hinge - structure as a
guide, and to leave the question of their final nomenclature till the

Many thousands of specimens, recent and fossi 1 , were studied ;
many hundreds of the recent forms had to be opened by boiling in
a test-tube in weak caustic soda, before they could be examined
under the microscope (1-in. objective), and a very large number of
the fossil forms had to be scrutinized three or four times, individually,
under a lens.

In the end seventeen well-marked forms were discriminated, of
which two are extinct, whilst one has not as yet been found, either
recent or fossil, in these Isles, although it possibly does occur,
thus leaving fourteen species known to be living in Britain.

To attempt subdivision of the genus and allot sectional names
on so few forms is to court disaster more complete than has
overtaken others with more extensive material to hand.

Clessin (35) divided the genus into three groups :

1. FLUAIININA, type: P. amnicum, Mull.

2. Hi VULINA, type : P. supinum, Schmidt.

3. FOSSARINA, type : P. obtusale, 0. Pfr.

His first group, as Sterki (166) has already shown, was based
on a misapprehension of the cardinal tooth of the right valve of
P. arnnicum, which he thought was double ; whilst his other groups
prove to be incongruous mixtures.

Westerlund (184) followed Clessin, but added a totally un-
necessary fourth group for the " deep-water " forms.

Ball's grouping (49) unhappily does not give promise of any
greater permanence, and one can only hope that Dr. Sterki, who is
working at the American species, may, with the plentiful examples
at his command, be able to attain better results.

The seventeen forms in question in this paper are capable,
however, of being roughly classed. Thus P. anniictim and


P. astartoides stand by themselves distinct from the rest. P. ccicer-
tanum, P. nitidum, P. personatum, and P. pusillum, with probably
P. milium, form a group of transitional forms, that is linked on
the one hand through P. pulcliellum with P. sultruncatum,
P. henslowanum, P. supinum, and P. parvulum ; and on the other
hand, through P. steenbuchii with P. lilljeborc/ii, P. hibernicum,
and P. obtusale. P. vincentianum, with its depressed ligament-pit,
is a form apart.


The history of the establishment of the several species here
recognized and the varying forms admitted by successive con-
chologists of note is briefly as follows :

1774. 0. F. Miiller described (123), but did not figure, nor cite
any figure, his Tellina amnicum. Concerning the identity
of this species there fortunately is no doubt, although a
large synonymy now follows the name.

1791. Gmelin described (97) a form under the name of Tellina
pusilla, referring to a figure by Schroter. The description
is inadequate for modern purposes : the figure conveys the
impression of a strongly striate form, such as P. pulchellum
or a young P. amnicum, and the outline rather favours the
latter. The name was used by Turton, Brown and others
for any or all of the smaller species of the genus, and since
it is impossible to say what Gmelin's shell was, the use of
the name must date from Jenyns, who first circumscribed
the species, as we know it.

1795. Poli described (138) and figured Cardium casertanum.
Neither figure nor description would enable one to identify
the species with certainly, but specimens sent me by Prof.
Bellini from the type locality, where it appears to be the
only species present, confirm the traditional belief on the
Continent that it is the same as Alder's P. cinereum.
1801. Draparnaud (51) created Cydas fontinalis for certain forms
obviously belonging to Pisidium. His description is, how-
ever, too meagre, and his figures, published in 1805 (52,
pi. x.), too rough to enable one to say exactly what they were;
whilst, unfortunately, his specimens have been lost. If a
guess might be hazarded from the representations, it would
be that the type and var. y were P. casertanum, and the var. ft
one of the smaller species. The name has been largely
used on the Continent for forms identical with that taken
in these pages as P. casertanum (Poli). It would therefore
seem advisable to drop the name altogether.

Draparnaud's only other species referable to Pisidium
was his (7. palustris, a synonym for P. amidcum.
1818. Lamarck (92) separated out a small tumid form to which
he gave the name Cydas obfusalis. The description was


not adequate, still it sufficiently fits the form to which
Jenyns subsequently applied it.

Lamarck's other two species referable to Pisidium are:
Ci/clas obliqua ( = Pisidinm amnicum) and Ct/clas fontinalis.

1821. C. Pfciffer (134) defined the genus Pisidium and placed in
it : 1. P. obliquum (Lam.), 2. P. obtusale (Lam.), and 3.
J\ foHftiiah (Dnip.). It is doubtful if the latter were the
same as Draparnaud's species, and the descriptions and
figures are equally vague.

1825. Sheppard (163) discovered and named Tellina henslowana.
His characterization leaves no doubt as to his species, which
i.s never questioned.

1832. Jenyns published his classical memoir (83) from which dates
our present knowledge of the British Pisidia. He detected
two additional species, and had he only been aware of the
value of the hinge-characters, would certainly have added
more, for some of his species undoubtedly combined more
than one form. His descriptions are full, but the figures,
though beautifully drawn, are not accurate representations
from the scientific point of view, as a careful comparison
of them with original specimens at Bath showed. His
species were :

1. P. obtusale, Pfeiffer.

2. P. pusillum, nobis.* (The extreme variety fig. 5

would probably, could it be
opened, prove to be P. per-

3. P. nitidum, nobis.

* 4. P. L rukheUam, nobis , ^^ ^^ tQ be wom

I \ examples of the oval form

var. 2. (This, as well known, proved

to be P. milium, Held.)

5. P. hcntlowianum, nobis.*

var. /3. (This was a perfect speci-

men of P. subtriincatum.)

6. P. amnicum, nobis.*

Jenyns, when he wrote his paper, was not acquainted
with the form here designated P. casertanum, but his
collection contains specimens of P. cinereum, Alder, sent
him by that naturalist, as well as P. yibba (seemingly an
oval form of P. nitidum) and P. fortitude (= subtrun-
calum), both from Alder, who in 1838 put them in Jenyns'

* Jen yns adopted the current botanical method of nomenclature in which

1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Online LibraryBritish Museum (Natural History). Dept. of ZoologyCatalogue of the British species of pisidium (recent & fossil) in the collections of the British Museum (Natural History), with notes on those of western Europe → online text (page 1 of 17)