38 G- O. Sars. 



Rem ark S. — This form is closely allied to D. fasciata, 

 and undoubtedly belongs to the same genus. It is, how- 

 ever, at once distinguished by the absolute absence of the 

 dark transverse band across the back so characteristic of 

 D. fasciata. On a closer comparison also the shape of the 

 shell is found to be somewhat different, the posterior ex- 

 tremity being far less tapered. It moreover reaches to a 

 considerably larger size than does D. fasciata. 



Occurrence. — I have onty had the opportunity of ex- 

 amining a solitar}'^ specimen of this form, which was found 

 in one of my aquaria prepared with mud from China. 



17. Ilyocypris dentifera, G. O. Sars, n. sp. 



(PL IV, figs. 8, 8 a— c). 

 Specific Characters. — Female. Shell rather com- 

 pressed, seen laterally, oval quadrangular in form, greatest 

 height somewhat exceeding half the length and occurring 

 quite in front, dorsal margin straight, forming above the 

 eye an angular bend, ventral deeply sinuated, both extre- 

 mities obtusely truncated, the anterior one considerably 

 broader than the posterior; — seen dorsally, narrow oblong 

 in form, somewhat constricted in front of the middle and 

 slightly dilated behind, anterior extremity acuminate, post- 

 erior more obtuse. Valves subequal, each exhibiting behind 

 a thin hyaline rim, inside which a series of about 12 strong, 

 posteriorly-pointing denticles occurs, anterior edge very mi- 

 nutely spinulose throughout ; surface of shell coarseW granu- 

 lar or minutely areolated, and clothed on each extremity 

 with scattered hairs. E3^e rather small and distant from 

 the dorsal margin. Caudal rami comparatively small and 



