108 

 36. llyocypris gibba (Ramdohr). 



(PI. L, fig. 1). 



Cypris gibba, Ramdohr, Magaz. d. Gesellsch. naturf. Freunde zu Berlin 1808, 



Vol. II, p. 41, PI. III. 



Syn: llyocypris gibba var. bicornis, Kaufmann. 



Specific Characters. Female. Shell resembling in general shape that o 

 the preceding species, though perhaps a little more elongate in proportion tc 

 the height, being however highly distinguished by the presence of 3 pairs o 

 well-marked lateral projections, especially very conspicuous in the dorsal o; 

 ventral aspect of the shell. Of the projections the one pair, located in fron 

 of the middle, is slightly umboniform, the other 2, located farther behind, an 

 more sharply marked off, but rather unequal in size, the smaller one occurring 

 near the ventral face, the larger more dorsally and forming a very prominen 

 recurved horn-like process. Structure of the several limbs almost exactly as ir 

 the preceding species. 



Colour whitish grey, generally lighter than in /. biplicata. 



Length of adult female about 1 mm. 



Male unknown. 



Remarks. This form was recorded as early as the year 1808 by Ram- 

 dohr as a species of Cypris, the specific name proposed by him alluding 

 apparently to the peculiar gibberiform lateral projections of the shell. B> 

 Kaufmann and Masi it has been described as merely an occasional variety 

 (bicornis) of the preceding species, which is regarded by them as the typica 

 /. gibba. This I think cannot properly be sanctioned. In our country and also 

 according to Dr. Aim, in Sweden the present form is much the predominant 

 and as it unquestionably is the same as that originally observed by Ramdohr 

 it ought in any case to be regarded as the typical /. gibba. In my opinion 

 it should moreover be kept apart from the preceding form as a particular, 

 though closely allied species. True, in some cases, especially in quite youn<i 

 specimens, the peculiar lateral projections of the shell distinguishing the pre- 

 sent species may appear much reduced in size; but I have never found th< 

 to be wholly absent as in the preceding species. 



Occurrence. This form is very common around Christiania, occurring 

 often in great abundance in small shallow ponds and ditches with clayey 

 bottom. In behaviour it agrees with the preceding species, though it has 

 appeared to me to be somewhat more agile, being often seen to swii 

 rather quickly through the water. 



Distribution. Throughout Europe, ? North America. 



len 



