141 



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 unequal 

 valves, five or more, united together at the extremity of a cartilaginous 

 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 connecting membrane. These 

 are all supported by a strong cartilage-membranous, flexible tube, which 

 is capable of being elongated or contracted at the will of the animal. 



A. Itfvis and A. striata are both said by Bosc, Hist, des Coquettes, Tome n. 

 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 ani- 

 mal, 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 Petrifica- 

 tions, PI. LIU. 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 rny 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 Trigonellites, 

 not seeing any reason for supposing them to belong to the genus Anatifa, 

 nor 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- 



VOL. III. I I 



