62 Fresh-water Biology 



(Continued from page 60) 



15_Swimming antennae of female two branched, the dorsal with many lateral and ter- 

 minal set£e (Sididae)— 16 



—Animal enclosed in a large globular, transparent, gelatinous case open ventrally and 

 forming two valves. Antennae of female with single ramus— (Holope did ae) ..... 

 Holopedium 



16— Dorsal ramus 3-jointed, ventral ramus 2-jointed; beak present (fig. 2) Sida 



— Dorsal ramus 2-jointed; ventral ramus 3-jointed 17 



17 — Dorsal ramus with interior process or expansion on basal joint Latona 



— Dorsal ramus without process 18 



18_Pocterior margin of shell valves with several long setae; Eyes dorsal far from in- 

 sertion of antennule — Latonopsis. Eye ventral or in middle of head. . . Pseudosida 

 — Posterior margin of shell valves without setae (fig. 12) Diaphanosoma 



19_Second antennae with superior branch 4-segmented; inferior branch 3-segmented. .20 

 — Second antennae with both branches 3-segmented Chydoridae — 28 



20— With 5 pairs of feet; first antennae small, if rarely large (as in Moina) then not in- 

 serted at anterior end of head; intestine with 2 hepatic caeca,. . . .Daphnidae — 21 

 — First antenna long; often with 6 pairs of feet; usuaUy no hepatic caeca 22 



21— Head of female with beak. Head keeled above, no transverse suture on neck, shell 

 with polygonal marks and with posterior spine (fig. 1)— Daphne; spine on shell 

 produced in a straight line with the ventral margin, shell with indistinct net like 

 markings— Scapholeberis; spine absent or very short and blunt; markings of 



transverse lines (fig. 5) Simocephalus 



—Head without a beak. First antenna of female very short, head small and depressed 

 (fig. 6).— Ceriodaphnla; first antenna large, head high Moina 



22— First antenna large and fixed; 6 pairs of feet (fig. 11)— Bosminid.ae Bosmina 



—First antenna long and freely movable Macrothricidae— 23 



23 — Intestine convolute 24 



— Intestine simple 26 



24 — Valves with spines at upper posterior angle Ophryoxus 



— Spines absent 25 



25_Convolutions of intestine in middle of body. Dorsal margin of shell with conspicuous 

 short backward pointing tooth about the middle— DrepanothrLx ; no dorsal tooth 



Parophryoxus 



—Convolutions of intestine in hind part of body. Posterior margin of shell truncated 

 — Acantholeberis; posterior margin rounded with slighly pointed protuberance in 

 middle Streblocerus 



26— Upper posterior margin of shell truncated diagonally; general form oval-triangular 

 the head constituting the apex. Ventral and posterior edges of valves enormously 



dilated Ilyocryptus 



—General form ovate, upper posterior margin of shell rounded, not truncated. Setae 

 on ventral margin of shell only 27 



27— Set« long, movable, spine like, and projecting in several directions (fig. 9) .... 



Macrothrix 



—Setse short and close set; mid-posterior extremity forming apex of roughly heart 



shaped shell Lathonura 



28— Anus at extremity of post abdomen; 2 hepatic setae (fig. 7) Eurycercus 



— Anus on dorsal side of post abdomen; no hepatic setae 29 



29_Head and back with high keel; post abdomen very long and slender; with marginal 



and lateral teeth (fig. 4) Camptocercus 



— Not with all the above characters ^" 



