The Cambridge natural history, Vol. 04 (of 10)

by Geoffrey Smith; D'Arcy Wentworth Thompson; Cecil Warburton; Walter Frank Raphael Weldon; Henry Woods

i. First antennae of female short.

α A median dorsal spine on posterior margin of carapace. Daphnia, O. F. Müller (Fig. [19]): first antennae of female not mobile. The head separated from the thorax only by a slight constriction or not at all. Cuticle with a quadrate rhomboid pattern. Ceriodaphnia, Dana: first antennae of female mobile. The head separated by a deep depression from the thorax. Cuticle with a polygonal pattern.

β A pair of ventral spines on posterior margin of carapace. Scapholeberis, Schoedler (Fig. [20]).

Fig. [20].—Scapholeberis mucronata, female, × 25. Oxford.

γ No spine on posterior margin of carapace. Simocephalus, Schoedler (Fig. [10], p. 39): the cuticle with a pattern of parallel branching ridges.

Fig. [21].—Moina rectirostris, female, × 24. Oxford.

ii. First antennae of female long, mobile. Moina, Baird (Figs. [16], 17, 21): median eye absent. Posterior margin of carapace without a spine.