98 Mr. W. Clark on the Animals of the BuUidse. 



Miss H. Nelson for having so kindly furnished me with fresh 

 specimens of Furcellaria fastigiata and Polyides rotundus during 

 this winter, collected near Cromer, which enabled me to make 

 the foregoing observations. 



X. — Observations on the Animals of the BuUidse. 

 By William Clark, Esq. 



To the Editors of the Annals of Natural History. 



Gentlemen, Norfolk Crescent, Bath, June 20, 1850. 



I PRESENT an account of some of the animals of the Bullidce 

 which inhabit the South Devon coast at Exmouth. They are 

 deposited in two groups, which undoubtedly as to essentials are 

 of the same tribe, and have long been adopted : the one. Bulla, 

 of which the B. hydatis and B. liynaria are the types, receives 

 the species with external testacea; the other, Bullcea, is repre- 

 sented by B. aperta, and is the receptacle of those with concealed 

 shells. From these roots some new genera have sprung, to meet 

 the supposed requirements of modern discoveries, most of which 

 are very minute ; some are without eyes, all are without distinct 

 tentacula or with the mere rudiments of them, and have the 

 pedal lobe more or less reflected laterally on itself, and partially 

 on the anterior end of the shell ; in others the lax margins of the 

 deep sinus, at the under part of the foot, which separate it from 

 the linear posterior portion, occasion it to appear nearly as simple 

 as in the usual run of the Gasteropoda ; this latter circumstance 

 has led to some mistakes, as will appear in descriptions of the 

 minute species. 



All the species I have met with have the invariable distin- 

 guishing character of the tribe, the gizzard consisting of three 

 testaceous, coriaceous or cartilaginous plates. I believe that 

 every true Bulla and Bullcea have one or the other of these ap- 

 pendages ; indeed it may be considered, that if an animal, how- 

 ever much it appears by the shell to belong to this family, has 

 not the shibboleth of the gizzard, it is an alien to it. 



The new genera of this tribe have been established by M. Loven, 

 amongst them Cylichna and Amphisphyra, but the minuter spe- 

 cies are so rarely met with alive, that they can scarcely be placed 

 with certainty ; and to add to the difficulty, the excellent Loven, 

 one of the most careful observers, has I think fallen into some 

 error with respect to the genus Cylichna, the generic diagnosis of 

 which would appear, from our present notes on two of the species 

 he has deposited therein, the B. cylindracea and B. truncata, not 

 to be founded on correct bases. But what naturalist does not 



