OF DENISON UNIVERSITY. 9 



Cypris crenata, sp,n. 

 [Plate II, Figs. 22-32. 



Cypris STp (?), . . . C. H. Turner. Bull. Sci. Lab. Denison Univ,, 

 Vol. VI, part II, p. 71; pi. II, figs, ii, 13. 



The shell is equivalve, very thin, the free margins of one valve 

 is bordered with blunt teeth. The ventral margins of both valves 

 bear hairs. Shell reticulated with contorted lines, the reticulations 

 are most distinct on the cephalic portion of valve. Lucid spots 

 about nine, sub-central. Color, various shades of greenish yellow. 

 The caudal half of shell of male appears to be marked with concen- 

 tric retort shaped lines. Since the shell is very thin this appearance 

 may be due to the presence of spermatozoa or spermatophores within 

 the shell. 



Viewed from the side [fig. 22] the shell is sub-reniform, highest 

 about the middle, cephalic and caudal extremities about the same 

 width. Caudal, dorsal, and cephalic margins convex ; ventral 

 margin nearly straight, slightly convex, at the middle. 



Viewed from above [fig. 23] the shell is sub-oval, widest behind 

 the middle. Caudal margin rounded, cephalic margin bluntly 

 pointed. Hinge line sinuate. 



Viewed from below [fig. 24] same as when viewed from above. 

 Line of contact of valves sinuate. 



Viewed from end [fig. 25] shell is oval, a little higher than 

 wide. 



Antennules [fig. 25] and antennae as usual in genus Cypris. 



The mandible [fig. 26] terminates in four large teeth, between 

 each two of these teeth there is a short, slender rod. The mandibular 

 palp consists of four joints. The first joint is very large, about as 

 large as the combined lengths of the other three ; it bears about the 

 middle ot its dorsal surface a branchial appendage, which in turn 

 bears four long setae ; and from the distal fifth of its ventral surface 

 arises two long setae. The antipenultimate joint is very short ; from 

 the distal half of its dorsal surface arises two long setae and one short 

 one. The penultimate joint is long ; from its disto-dorsal extremity 

 arise three long and one short setae ; from the disto-ventral angle of 

 the shell arises two shori setae. The terminal joint is very narrow 

 and about as short as the antipenultimate joint ; at its tip it bears four 

 short claws. 



