1889.] ON SOME FRESHWATER OSTRACODA AND COPEPODA. 31 



striation, which of course is an infallible criterion of the adult 

 state. A little in front of the middle the ventral edge of 

 either valve forms a small rounded lobe] projecting inwards, 

 that of the left side overlapping the other, when the valves 

 are closed (see PI. I, fig. 8). On the inner side each valve 

 exhibits (see PI. V, fig. 1) a well-marked duplicative, the an- 

 terior part of which is very broad and shelf-like, being bounded 

 by a curved line crossing the extremity at a considerable distance 

 from the edge. The duplicature is continued along the ventral 

 edge, being however here rather narrow, but at the posterior 

 extremity it becomes again somewhat broader, though by far not 

 reaching the large size as anteriorly. 



The colour of the shell in the living state of the animal is 

 light greenish, variegated with indistinct yellowish shades, this co- 

 lour being chiefly due to the enclosed body. The coecal appendages 

 of the intestine appear very distinctly as a narrow diagonal band of 

 a bright yellowish green colour, running from the centre of each 

 valve to the posterior extremity. Moreover the eye is seen 

 with great distinctness through the shell, as also the bright 

 reddish coloured eggs contained in the posterior part of the 

 body. Those limbs, which admit of being extended beyond 

 the shell exhibit a light brownish hue. 



The eye (see PI. V, flg. 1) is very large, and its outer 

 faces exhibit a most brillant irridescent lustre; each of them 

 would seem to be divided into 3 facets, but their limitation is 

 by no means sharply defined. 



As to the several limbs, their structure agrees in all 

 essential points with that minutely described above in Cyprinotus 

 dentato-marginatus, and hence I do not regard it necessary to 

 give separate descriptions of each pair — though closely exami- 

 n ed by dissection — , but only to point out the more marked 

 differences occurring in some of them and indicating the generic 

 distinction between these two forms. On PI. V, fig. 1 I have 

 however given an accurate drawing of the animal — lateral view — 

 exhibiting all its limbs in their natural situation, as it appears 



