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



As in other male Cyprididæ, the palps of the 2nd pair of maxillae 

 are modified to hooked prehensile organs and may at times, together 

 with the copulative apparatus, be seen extruded beyond the shell. The 

 mucous glands are constructed in the usual manner, and are faintly traced 

 through the shell posteriorly. 



The colour is generally more uniformly yellowish, than in the female, 

 being sometimes tinged with brownish, sometimes with a light ochraceous 

 colour. 



Observations. This form developed in great abundance in some 

 of my aquaria, and was successfully domesticated during several successive 

 seasons. As to habits, it is, on the whole, much more active than its 

 ally C. sydneia, being often found to swim through the water with con- 

 siderable speed. Unlike what is generally the case with the Cyprididæ, 

 male specimens were, at all times of the season, nearly as numerous as 

 female ones. They are very passionate, swimming actively about in 

 pursuit of the females, and it did not seldom happen that even one and 

 the same female was seen to be solicited by 2 or 3 males at the same 

 time. The copulation is generally eftected at the bottom, after the 2 

 sexes haA'e remained in company for some time. 



Gen.: Oyclocypris, Brady t<c Norman. 



14. Cyclocypris pusilla, G. O. Sars, n. sp. 



(PI. 5, fig. 5, a-b.) 



Specific Characters. Shell not very tumid, the width and height 

 being about equal : — seen laterally, rounded oval in form, somewhat 

 higher behind than anteriorly, dorsal margin slightly arcuate, ventral nearly 

 straight, anterior extremity obliquely rounded, posterior blunted : — seen 

 from above, regularly oval, with the greatest width about the middle, 

 anterior extremity somewhat narrower than the posterior. Valves but 

 slighth' unequal, the right one being the larger and overlapping the left, 

 anteriorly, by a hyaline border. Surface of shell smooth, being only hairy 

 towards each extremity. Colour dark sepia. Length of adult female 

 0,48 mm. 



Remarks. This small form bears a considerable resemblance in its 

 general appearance to the European species, C. ovimi Jurine, but seems 

 to be specifically distinct, to judge from its rather different colour, which is 

 dark sepia, instead of light brown or orange, as in the European form. 

 There would also seem to be some slight differences in the form of the shell. 



