8io 



FRESH-WATER BIOLOGY 



27 (26) Shell with weak tubercles, knobs, and furrows. Natatory setae 

 reaching scarcely to tips of terminal claws. 



Ilyocypris hradyi Sars 1890. 



Length about as /. gibha. Height 

 of female 0.45 to 0.5 mm., breadth 

 0.32 to 0.5 mm. Male slightly larger. 

 Scarcely free swimming, but creeps or 

 burrows. Shell weakly tuberculate 

 and not furrowed posterodorsally. 

 Habitat and occurrence as /. gihba. 

 Furca strong curved, and much broad- 

 ened at base. About ten times as long 

 as width in middle. Dorsal seta plu- 

 mose and bent near tip. Distal half 

 of dorsal part of furca ciliate. These 

 two species are quite variable, thus 

 causing much confusion in diagnosis. 

 Both species are also found in Britain 

 and Germany. 



Fig. 1258. 

 Ilyocypris bradyi. (a) Furca, X 200; (b) 

 End of second leg, X 150; (c) Dorsal 

 view, X 45; (d) Side view, X 45- 



28 (29) Natatory setae of the second antenna shortened, no swimmers. 



Second leg with a beak-Hke end segment and a claw (Fig. 

 1268 b) Subfamily Herpetocypridinae . . 30 



29 (28) Natatory setae of the second antenna long, reaching at least to tips 



of terminal claws. Second leg as above. 



Subfamily Cypridinae . . 42 



30 (31) 



Furca abnormal, with three claws, — the usual dorsal seta being 

 replaced by a claw. Shell faintly longitudinally striated 

 (Fig. 1259) Ilyodromus Sars 1894. 



Only one species known in America. 



Ilyodromus pectinatus Sharpe 1908. 



Length 1. 10 to 1.18 mm. Shell with 

 reticulate patterns anteriorly and 

 posteriorly. Posterior edge of furca 

 decidedly pectinate. The only known 

 species of the genus with a pectinate 

 furca. In ponds and slowly flowing 

 streams, with Typha, Iris, Chara, etc. 

 South Carolina. 



Fig. 1259- 



Ilyodromus pectinatus. (o) Side view, X 45". 



(6) Furca> X 140. 



