THE 



CALCUTTA JOURNAL 



OF 



NATURAL HISTORY. 



Description of Camptoceras, a new genus of the Lymnceadoe, allied to An- 

 cylus, and of Tricula, a neiv type of form allied to Melania. By W. H. 

 Benson, Esq., Bengal Civil Service. 



Family. — HELICIDiE, Swainson. 

 Sub-fam. — LYMNACINiE, Sw. 

 Genus.— CAMPTOCERAS, Nobis. 



Testa elongata sinistrorsa, anfractibus paucis productis, baud con- 

 nexis, spira saliente-subrecta ; apertura oblonga, libera, integra; pe- 

 ristoraate acuto, continuo. 



Animal. Tentaculis duobus filiformibus obtusis munitum; oculia 

 magnis inter tentacula sitis ; proboscide medio cri; Pailio labia testae 

 haud transeunte. Pede brevi longitudinem aperturae vix superante. 



C. Terebra. Testa diaphanEi elongata, anfractibus tribus compressis 

 biangulatis, transverse striolatis, lineis longitudinalibus depressis de- 

 cussatis. 



Animali fuscato, versus spiram rubescente. 



This is a most interesting type, intermediate between Lymnsea, and 

 the other spiral shells of the family, and the short untwisted conical 

 forms which constitute the genus Ancylus. It is, in fact, an anoma- 

 lous Ancylus, to the animal of which it approaches more nearly than 

 to that of Lymnsea. It has still less affinity to that of Physa, which has 

 a considerably developed mantle. The motions of the animal are, 



VOL. III. NO. XIT. JANUARY 1843. S O 



