10 Mr. W. H. Bensou on the Genus Camptoceras. 



Genus Camptoceras, Benson. 

 (Character emendatus et auctus.) 

 Testa sinistrorsa, imperforata, elongato-elliptica, spira soluta, apice 

 acutiusculo, sutura late et profunde excavata (re vera omniuo 

 carente) ; aufractibus 3-4 angustis elongatis, superne et subtus 

 carinatis, lateribus planulatis ; apicali elongato-acumiiiato, longe 

 exserto ; ultimo autice superne desceudente, carinato ; apeitura 

 soluta, Integra, magna, sjnram non sequante, elongato-elliptica, 

 angustiuscula, superne et ad basin arcuatim angulata ; peristomate 

 acuto ; operculo nuUo. 



Species unica. 



C. Terehra, Benson. 



Testa elongato-elliptica, hyalina, vel albido-cornea, 

 lineis spiralibus, exiguis, vix elevatis, striis ob- 

 liquis coufertissime decussatis ; apertura verti- 

 cal!, elliptica; peristomate acuto, vix expansi- 

 usculo. 



I 



Long, vix 9, plerumque 6 ad 7 mill. 



Diam. 3 mill. Long, apert. exempl. majoris 4 mill. 



C Terebra. 



Syn. C. Terebra, Benson, Calcutta Journ. Nat. Hist. 1842. 

 Ilab. in lacu paludoso prope Moradabad, agro Robillano. 



Animal, 



Animal tentaculis duobus filiformibus, obtusis, oculis magnis inter 

 tentacula sitis, proboscideque mediocri muuitum ; pallio labia testse 

 hand transeunte ; pede brevi, longitudinem aperturse \ix superante. 



The form of the tentacula and the position of the eyes, situated 

 between the filiform tentacula, and sessile on the head (not, as 

 in Lymnaa, occupying the fore part of the widened base of the 

 triangular tentacula), at once distinguish the animal from that of 

 Lymnaa. In Camptoceras the eyes are large in proportion to 

 the size of the animal, while in Lymnaa they present only a 

 minute black point, even in individuals of large size. In Ancylus 

 also the eyes are small, and inserted in two lateral lobes pro- 

 ceeding from the tentacular laminse, which are triangular and 

 truncated*. The shortness of the foot, however, the sluggish 

 movements of the mollusk, and its strong adhesion to smooth 

 surfaces, point to an affinity with Ancylus, which, instead of 

 presenting the elongate, imperfectly rolled, acutely spiral cone 



* Vide Dvipuy, Mollusques de France. 



