30 G O. SARS. M.-N. Kl. 



besicles, the mucous glands may be rather clearly traced through the hind 

 part of the shell. 



Observations. This form was only found in 2 of my aquaria, and 

 did not occur in any abundance. It was at first caught quite occasionally by 

 taking up small quantities of the deposit at the bottom b}^ the aid of a 

 dipping tube, and submitting that to a closer examination. Sometimes, 

 however, solitary specimens were observed creeping up the walls of the 

 aquarium, and in such cases it could be at once dcstinguishcd, by the 

 aid of a hand-magnifier, from other Cyprididae occuring in the same aqua- 

 rium. It was also seen, occasionally, to swim rather quickly through the 

 water in a similar manner to tliat observed in other species of the genus. 



Gen. : Cypris, ^luller. 



II. Cypris corpulenta,, G. O. Sars, n. sp. 



(PI. 5, fig. 2, a— c.) 



Specific Characters. Shell all over densely hairy, and extremely 

 tumid, the greatest width even considerably exceeding the height, — seen 

 lateral]}', of irregular oval form, with the greatest height somewhat in 

 front of the middle, dorsal margin subangular just above the eye, and 

 sloping gentl}- behind, ventral sinuated in the middle, the sinus being 

 limited anteriorly by a slight expansion, anterior extremity broadly rounded, 

 posterior obtuse and not expanded below : — seen dorsally, broadly oval, 

 side-contours evenly curved, anterior extremity more pointed than the 

 posterior. Valves subequal, both exhibiting, in front, a rather broad pellucid 

 border surmounted by a narrow hyaline rim, inner duplicatures rather 

 broad. Surface of shell smooth. Appendages of the typical structure. 

 Caudal rami very narrow, linear, with the terminal claws slender. Colour 

 yellowish brown clouded, dorsally, with dark green. Length of adult 

 female 2,io mm. 



Remarks. This is a quite t3'pical Cypris, being somewhat inter- 

 mediate in character between the European species C. pubera and virens, 

 though well defined from an}' of them. It is chiefl}' characterised by the 

 densely hairy and extremeh' tumid shell, which latter characteristic has 

 given rise to the specific name. 



Description of the female. 



The length of adult specimens somewhat exceeds 2 mm., antl this 



form accordingh' belongs to the larger sized species. 



The shell is extremely tumid, being considerably wider than it is 



broad, and is all over densely hairy. 



