CANIDIA. 



the form and sculpture of the shell do not contravene such a dis- 

 position of Clea, its fluviatile distribution being actually the 

 strongest argument for considering it a Melania. As to the 

 genus Canidea, the differential characters are slight and of 

 specific value only, except that the margin of the aperture is 

 sinuated in front in all the species, and this may serve as a con- 

 venient means of dividing the genus Clea into two groups, one 

 of which may bear the name of Ganidea as a subgenus. The 

 differences in operculum and dentition pointed out by Brot are 

 unimportant. The geographical distribution of the genus com- 

 prises the Malaysian Peninsula and Archipelago. It would be 

 interesting to ascertain whether the waters inhabited are really 

 fresh, or perhaps brackish. 



For the species, I follow the monograph by Dr. A. Brot, pub- 

 lished in the " Journal de Conchy liologie," 1876. 



C. NIGRICANS, A. Adams. PI. 81, figs. 445, 446. 



Epidermis dark olive, aperture light chocolate. Length, 28 mill. 



Sarawak, Borneo. 



C.funesta, A. Adams, an unfigured species from Malacca, does 

 not appear to differ specifically, judging from the description. 



Subgenus Canidia, A. Ad. 



C. HELENA, Meder. PL 81, figs. 447, 448. 



Yellowish olive, with two chestnut bands. Length, 20 mill. 



,/aoa. 



I do not find any good characters by which to separate C. 

 Theminckiana, Petit (fig. 448), an immature shell. 



C. TENUICOSTATA, Brot. PL 81, fig. 449. 



Brown, without bands. Length, 21 mill. 



Pexabury, Siam. 

 Perhaps a variety of G. Helena. 



C. BAUDONTANA, Mabille and Le Mesle. PL 81, fig. 450. 



Yellowish olive, the bands chestnut-brown. Length, 30 mill. 



Houdong, Cambodia. 



With a longer spire than C. Helena, and three bands, this 

 still be only a variety of it. 



