THE WATER FLEAS (CLADOCERA) 



709 



lar^e, some distance from apex of rostrum. Intestine convoluted, with small hepatic ceca. 



J with hook on first foot; vas deferens opens near claws. Length, J, to 1.2 mm. Color 

 transparent-yellowish. 



Maine. New Hampshire; among weeds in lakes. The difference in antennary setae of I and 



9 holds for all specimens hitherto seen. 



iP.2 MM 



Fig. iioi. Parophryoxus lubulatus. (After Doolittle.) 



89 (88) 



Strehlocerus Sars 1862 



90 



Setae : animal small, spherical. 



1-1-3 



Body round-oval, not compressed or crested. Labrum with large, serrate, acute process. 

 AnteimulesMarge, flat, bent, or rather twisted, broadened in distal part; with lateral sense- 

 hair near base, several hairs on posterior face, rows of fine hairs, and subequal olfactory setae. 

 Post-abdomen bilobed; the pre-anal part compressed, semi-circular; the anal part rounded^ 

 with fine spines or hairs. Claws small, curved, with several equal minute denticles on con- 

 cave edge. Five pairs of feet. Intestine convoluted, with small hepatic ceca. $ (European, 

 of 5. serricaudatus) small, triangular, much Uke $ ; first foot without hook. 



90 (91) Dorsal margin of valves smooth. 



Strehlocerus serricaudatus (Fischer) 1849. 

 0.1 MM.j^_^ . Pre-anal part of post-abdo- 



men with serrate margin and 

 bearing rows of fine hairs. 

 Anterior margin of antennule 

 somewhat toothed. Color 

 whitish-opaque to yellowish. 

 Length, 9> ca. 0.5 mm.; $, 

 ca. 0.25 mm. 



Rare but widely distributed 

 in weedy pools and margins of 

 lakes. Reported from New 

 England, Wisconsin, Nebraska, 

 Louisiana, Colorado, Califor- 

 nia. 



Fig. 1102. 



Strehlocerus serricau- 

 datus. 



91 (90) Valves reticulated, the edges of the reticulations making scale-like 



ridges, which give the dorsal margin a serrate appearance. 



0.05 MM I « Strehlocerus pygmaeus Sars 1901. 



Pre-anal part of post-abdomen not serrate, with 4-5 rows 

 of fine hairs. Color grayish white, opaque, to nearly black 

 in ephippial 9 • ^ unknown. 



Length, 9, 0.2-0.25 mm. The smallest member of the 

 family and one of the smallest of the group. Louisiana, in 

 weedy pools, with S. serricaudatus. 



Fig. 1103. Strehlocerus pygmaeus. 



