702 



FRESH-WATER BIOLOGY 



59(58) Fornices of ordinary form; eye large. . .. . . > T . . ; ; . . . 60 



60 (61) Head inflated in front of antennules. Small form not exceeding 

 0.7 mm Ceriodaphnia pulchella Sars 1862. 



Form of ordinary type. Head rounded in front; inflated in 

 region behind eye, angulated in front of antennules. Valves retic- 

 ulated but not plainly so. Post-abdomen not sinuate above anal 

 spines, which number 7-10. Length, 9 , 0.4-0.7 mm.; rf, 0.5 mm. 



Found among weeds and limnetic in lakes and in pools; reported 

 from all regions. Forms agreeing perfectly with this description 

 may be found, as also quadrangula forms, but other varieties occur 

 which are difficult to assign to either species, but which so closely 

 agree with them as to render it impossible to make a new species 

 for them. 



i 



FIG. 1084. Ceriodaphnia 

 pulchella. 



6 1 (60) Head angulated but not inflated in front of antennules. Length to 

 i.o mm. . . Ceriodaphnia quadrangula (O. F. Muller) 1785. 



General form like reticulata. Valves reticulated, often not plainly marked. Antennules 

 with lateral sense-hair near apex. Post-abdomen narrowing toward apex, often, but not always, 

 sinuate above anal spines; these number 7-9. Claws large, denticulate. $ antennules with 

 long flagellum, hook-like at tip. Color transparent to pinkish opaque. Length, ? , to i.o 

 mm.; , to o6 mm. 



Common in all regions, found both among 

 weeds and limnetic. C scitula Herrick seems 

 to be a large variety of this species. 



FIGS. 1085, 1086. Ceriodaphnia quadrangula. 



62 (56, 57) Post-abdomen very broad, obliquely truncate 63 



63 (64) Vertex evenly rounded, without spines. Antennules moderate. 



Ceriodaphnia laticaudata P. E. Muller 1867. 



General form round. Valves ventricose 

 below. Post-abdomen large, dilated near 

 middle, obliquely truncated and bearing 

 8-1 1 spines on lower margin. Claws long, 

 denticulate. Color transparent or opaque, 

 through red and red-brown to nearly black. 

 Length, 9, to i.o mm., but not seen larger 

 than 0.7 mm. in United States; $ , to 0.7 

 mm. 



Wisconsin and Minnesota to Florida, Lou- 

 isiana, and Texas. 



This species is C. consors Birge. 



FIG. 1087. Ceriodaphnia laticaudata. 

 0.1 MM. , 



