6o Records of the Indian Museum. [Vol. XIX, 



Anterior lip close behind the anterior adductor muscle. Gills 

 small and narrow, non-plicate and homorhabdic. Attachments of 

 gills similar to those in Solen. No division into oesophageal and 

 cardiac chambers. Coecum of the cr3^stalline st3de from the 

 anterior portion of the ventral aspect of the pyloric chamber. 

 Intestine of two simple limbs. Digestive gland passing over the 

 anterior adductor muscle. Heart placed in the middle of the 

 pericardial chamber ; blood red. A single circumpallial nerve. 



The anatomical researches of Bloomer on Ceratisolen has 

 disclosed some facts which help to determine the relation of Cerati- 

 solen with other genera of the family. The general conformation 

 of the body shows that the animal is less elongated than Ensis 

 and Solen but more so than Neosolen, Subcultellus and Cidtellus ; 

 the position of the posterior adductor muscle near the hinder end 

 of the bod}'- is certainly compatible with the view that the 

 posterior end has not elongated behind the attachment of the 

 muscle. The genus, however, resembles the genus Subcultellus 

 {Cultellus pellucidus) most closely in having a fourth aperture in 

 continuation of the pedal aperture (a condition of great morpholo- 

 gical importance), and in several other points, viz. in the separa- 

 tion of siphonal tubes, attachments of gills, relation of the pedal 

 fibres of retractor pedis anterior muscle with the longitudinal layer 

 of muscles, and in the direction of the coecum of the cr^^stalline 

 style, but differs from the latter in having simple, non-plicate gills, 

 in the position of the heart and digestive gland. Differing from 

 Ensis in the attachments of the gills, arrangement of the pedal 

 fibres of the retractor pedis anterior muscle, direction of the 

 coecum and its mode of origin, and in the presence of a single 

 circumpallial nerve, the genus cannot be assigned an intermediate 

 stage between Ensis and Subcultellus , giving origin to the former 

 genus by the fusion of the siphonal tubes and separation of the 

 fourth aperture. It, however, resembles the genus Ensis in the 

 extension of the digestive gland over the anterior adductor muscle, 

 a character absent in Subcultellus but present in Cultellus. Thus 

 it obviously follows that although the genera Ceratisolen and 

 Subcultellus are more or less related to each other and to Ensis on 

 the one hand and Cultellus on the other, they cannot be con- 

 sidered to form a connecting link between the above genera in the 

 direct line of ancestry but to represent diverging offshoots from 

 the same stock. 



Gen. Subcultellus, gen. nov. 



1810. Cultellus (pars), Schumacher, Essai Nouv. Syst. Habit, des 



Vei's. Testace, pp. 43, 130, pi. vii, fig. 4. 

 1835. Solen pellucidus, Pennant, Lamarck, Hist. Nat. Aniin. Sans. 



Vert., VI, p. 56. 

 1851. Ensis pellucidus, Pennant in Gray, Cat. Brit. Mus., VII, p. 60. 

 1858. Ensis (pars), Adams, Gen. Recent Moll., II, p. 342. 

 1874. C. pellucidus, Pennant in Reeve, Conch. Icon., fig. 4. 

 1887. Cultellus, Schum. (pars), Fischer, Man. Conch., p. i,ioq. 

 1889. Cultellus, Schum. (pars), Clessin in Martini-Chamnitz, Condi. 



Cab. (Solanacea), XI, p. 38. 



