241 
but of one more specimen, which was in the valuable collection of 
Mr. Donovan, and exhibited in the London Museum. 
CLX. Anatifa. A cuneiform multivalve, composed of several un- 
equal valves, five or more, united together at the extremity of a car- 
tilaginous tube, fixed at its base. The opening without an operculum. 
This shell is in general composed of five principal valves, to which 
sometimes several smaller are united by a connectingmembrane. These 
are all supported bya strong cartilago-membranous, flexible tube, which 
is capable of being elongated or contracted at the will of the animal. 
A. Icevis and A. striata are both said by Bose, Hist, cles Coquilles, 
Tome ii. p. 172 and 173, to be found fossil. The latter of these is also 
said by Gmelin, System. Nat. p. 3210, to be sometimes found fossil. 
Neither of these statements are, I believe, supported by sufficient 
authority ; since all the substances which I find described, as the fossil 
remains of this animal, appear to be of a different origin. 
Some long and narrow fragments have been found on Mount Randen, 
in Switzerland, one of which is figured by Bourguet, Traite des Petrif- 
cations, PI. liii. No. 355, as Petit os d’Echinite ; and others are figured 
by Knorr , who also supposes that they are the teeth of an echinus. These 
are supposed by Bertrand, Dictionnaire des Fossiles, p. 156, to be the 
fossil remains of a shell of this species ; some of these fossils, which 
are in my collection, have decidedly the appearance of being echinal 
remains. Scheuchzer and others have described single valves, which, 
from their compressed and triangular form, they have been led to ima- 
gine were the remains of a shell of this genus. But these are the valves 
which I have already placed before you, under the genus Trigone llites, 
not seeing any reason for supposing them to belong to the genus 
Anatifa, or, indeed, to any other previously formed genus. 
The fossils to which I shall now call your attention are particularly 
interesting, not merely from the puzzling appearances, which serve, in 
a considerable degree, to conceal the origin of the fossil to which they 
belong, but also as they serve to account for the peculiar rugose and stri- 
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