ENTOMOSTRACA OF MINNESOTA. 813 



1887.— Cypridopsis vidua C. L. Herrick (86), p. 33; PI. IV, Fig. 1. 



1888.— Cypris vidua Sostaric (202), p. 46. 



1889. — Cypridopsis vidua Brady and Norman (31), p. 89. 



1891.— " vidua Wenzel Vdvra (221), pp. 75-77; Figs. 23, 23^-23*. 



1892.— " vidua C. H. Turner (212), p. 73. 



1894.— " vidua C. H. Turner (215), p. 19. 



1894.— '• vidua C. H. Turner (216). 



Length 0.54 mm. to 0.7 mm. Height 0.34 mm. Width 0.37 mm. 

 to 0.49 mm. 



The color of the tumid shell is yellowish green. The shell is cov- 

 ered with short sparse hairs and is marked with three characteristic 

 dark bands (PL LXXV, Figs. 5, 8). These bauds are confined to the 

 dorsal surface. 



Viewed from the side (PI. LXXV, Fig. 5) the shell is sub-reni- 

 form in outline, widest in the middle. Excepting a slight concavity 

 at the middle, the ventral margin is straight. The other margins are 

 strongly convex. Muscle impressions sub central. 



Viewed from above (PI. LXXV, Fig. 8) the shell is broadly orvid^ 

 being widest caudad of the middle. The two extremities are round- 

 ed, but the cephalic extremity is much more narrow than the other. 

 The sides are strongly convex and the hinge-line is straight. 



Viewed from below (PI. LXXV, Fig. 6) the shell has the same 

 general shape as when viewed from above. The contact line is sinuous 

 and there is a slight depression in the centre. 



Viewed from the cephalic end (PJ. LXXV, Fig. 9) the shell is a 

 broad oval, being wider than high. Contact line straight. 



The antenna is five-jointed (PI. LXXVI, Fig. 7). The terminal 

 joint is small. A projection from the outer angle of the distal ex- 

 tremity of the penultimate joint extends half way the length of the ter- 

 minal joint. Two of the terminal claws are stout and one of them 

 bears, on its inne margin, blunt teeth. The natatory setse extend to a 

 little beyond the tip of I he terminal claws and are plumose. 



The mandible is stout. The claws of the mandibular palp extend 

 to the tips of the mandibular teeth. The antepenultimate jointof the 

 palp bears a short, pectinated, dagger-shaped seta. As far as my ob- 

 servations go, the penultimate joint does not bear such a seta. The facfc 

 that the dagger-shaped seta found on the penultimate joint of some 

 Cppridce occurs on the side renders its detection quite difficult. 



The abdominal rami (PI. LXXVI, Fig. 4) are rudimentary, the 

 long slender terminal claw being longer than the ramus. In addition 

 to the terminal claw there is a shorter and more slender claw. 



Habitat: This species occurs in all kind of fresh water. I have 

 found it in small tanks, pools, ponds, lakes, creeks and small rivers. 

 It usually occurs in great numbeis. 



