262 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



reticulated and spotted; color dark; length 0.7 to 0.8 mm.; male 0.55 

 mm. The males have the abdomen very narrow for the entire length. 

 This species is considered rare elsewhere, but is not infrequent 

 near Minneapolis during August. 



Cliyclorus ovalis Kurz. 

 Plate LXIV, Fig. 11. 



Form oval, nearly twice as long as high; beak long; antennules 

 two-thirds as long as the beak, with one elongated sensory filament 

 above the others; pigment fleck nearly as large as the eye; antennae 

 small; shell margins heavily fringed anteriorly; post-abdomen of mod- 

 erate size, rounded at the end, with about eight teeth near the end; 

 shell smooth. Length 0.4 mm. 



This species is rather near G. sphmricus, differing in having the 

 shell smooth, antennae shorter and beak longer. This species is not 

 yet known in America. From G. lotus it differs in the single anten- 

 nulary flagellum and number of anal teeth. 



* Cbydorus c?elatus Schoedler. 



Plate LXIV, Fig. 12. 



Chydorus adunctus — Schoedler. 



This small species is about 0.4 mm. long and resembles the young 

 of G. glohosus in form, from which as well as from all known species it 

 is distinguished by the markings of the shell, which consist of series 

 of rounded elevations (or depressions'?) arranged parallel to the lower 

 margins of the shell and head. The description is very incomplete, 

 and the only other author who appears to have seen the animal is Kurz, 

 who adds that the sensory filaments of the antennsB are unequal in 

 height, and that the so-called elevations are really depressions. A 

 form with a few depressions about the edge and characters of this 

 species was once seen in the vicinity of Minneapolis. This is probably 

 a variety of G. sphcericus. 



Chydorus iiitidiis Schoedler. 

 Plate LXIV, Figs. 5, 6. 



Shell smooth and regularly punctate; the head resembles G. spceri- 

 cus, but the pigment fleck is much smaller than the eye, to which it is 

 much nearer than to the end of the beak; the post-abdomen is broader 

 near the end, and bears a row of 10 to 12 teeth on either side. 



Chydorus latus Sars. 



Of moderate size, oval, rounded behind. A slight depression be- 

 tween head and body. Beak long, slender and curved. Macula quad- 



