330 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
sufficiently modified to include the American forms that propagate 
sexually. It is presumed that Professor Wenzel Vavra, who objects 
to the genus Erpetocypris (221), will also object to this one. The species 
of this group, however, are closely related both anatomically and 
physiologically, and it is thought that most workers will welcome the 
division of the old genus Cypris into the several genera here given. 
Shell rather thin, compressed, oval or sub-triangular, height ex- 
ceeding half the length, dorsal margin strongly arched, ventral almost 
straight. Valves usually unequal, the left valve overlapping the 
right. The free edges of left valve smooth, cephalic and caudal 
extremity usually bordered with a hyaline flange. The free cephalic 
end of right valve usually armed with tuberculiform teeth. Natatory 
setze of antennze reach beyond the tip of the terminal claw. Abdomi- 
nal rami are slender, with smooth or very finely pectinated claws. 
Propagation is sexual. Copulative organs are small, with an outer 
linguiform obtuse plate. The cylindrical core of Zenker’s organ bears 
numerous wreaths of spines, 
Cyprinotus incongruens Ramdobr. 
PLATE LXVIII, Figs. 9-16. 
1808.—Cypris incongruens Ramdohr (173), p. 86; Taf. III, Figs. 1-12, 15, 16, 18-20. 
1820.—Monoculus conchaceus Jurine (98), p. 171; Pl. XVII, Figs. 7-8. 
1820.— ruber Jurine (98), p. 172; Pl. XVIII, Figs. 3-4. 
1820.— ‘ aurantiacus Jurine (98), p. 173; Pl. XVIII, Figs. 5-12. 
1821.—Cypris fusca Straus (205), p. 59; Taf. I, Figs. 1-16. 
1844.— ‘‘ aurantia Zaddach (234), p. 37. 
1844.—? ‘‘ opthalma Koch (!02), H. 36, p. 17. 
1850.— ‘* aurantia Baird (5), p. 159; Taf. XIX, Fig. 13. 
1853.—. ‘‘ incongruens Lilljeborg (118), p. 119; Taf. IX, Figs. 6-7; Taf. XI, Figs. 
1-4; Taf. XII, Fig. 6. 
1855.— ‘* aurantiaS. Fischer (65), p. 650; Pl. I, Figs. 29-31, 60, 61. 
1868.— ‘‘ incongruens Brady (18), p. 73; Pl. X XIII, Figs. 16-22. 
1868.— ‘‘ fusca Fric and Nekut (70), p. 47, Fig. 28. 
1872.— ‘* fusca Fric (69), p. 212, Fig. 26. 
1889.— ‘‘ incongrwens Brady and Norman (31), p. 73; Pl. XII, Figs. 8-9. 
1891.— ‘* incongruens Wenzel Vavra (221), pp. 95-98; Figs. 32, 321-32°. 
1893.— ‘* incongruens C. H. Turner (213), p. 8; Pl. I, Figs. 9-16; Pl. II, Figs. 17-21. 
Length 1.35 mm. Height 0.75 mm. 
The shell is equivalve, one valve overlapping the other in front. 
The shell is yellowish brown in color and is covered with scattered 
hairs. 
Viewed from the side (Fig. 9) the shell is sub-reniform, widest near 
the middle. Both extremities rounded and of nearly the same width; 
the cephalic extremity may be a trifle narrower than the caudal. 
Ventral margin nearly straight, other margins convex. 
