SIDA. 107 



1. SiDA CRYSTALLINA. Tab. XII, figs. 3,4; Tab. XIII, 

 fig. 1 a-li. 



Daphne crystallina, Midler, Zool. Dau. Prod., No. 2405, 1776. 

 Daphnia CRYSTALLINA, Milller, Entomost., 9G, 1. 14, f. 1-4. 



— Latreille, Hist. Nat. Crust., iv, 230. 



— Bosc, Mem. d'Hist. Nat. Crust., ii, 281. 

 SiDA CRYSTALLINA, Struus, Mem. Mus. Hist. Nat., v. 



— M. Edwards, Hist. Nat. Crust., iii, 385. 



MoNOCULUs CRYSTALLINUS, Gmell/i, Liuu. Syst. Nat. edit. 13th, i, 



3000, No. 29. 



— Manuel, Enc. meth., vii, 724, t. 2G5, 



f. 15-18. 



— Fabricius, Eiit. Syst., ii, 493. 

 MoNOCULUS ELONGATUS, De Geer, Mem. servir Hist. lus., vii, 470, 



t. 29, f. 1-4, 1778. 



Carapace or shell elongate-ovate, very transparent, 

 truncate at inferior extremity. Head (t. XII, f. 3 a) large, 

 with a projecting plate at the posterior part (f. 3 a, q). 

 Eye large and round (t. XII, f. 3 /^, 3 a, c). Body within 

 the carapace very narrow, nearly straight. 



Abdomen has at the bend a projecting knob, with two 

 long seta) proceeding from it, and terminates in tw^o long, 

 stout claws, each of Avhich has three spines on its inner 

 edge (t. XIII, f. h). Between the knob and the termina- 

 ting claws the inferior edge is beset with two rows of about 

 twenty short spines. 



The superior antenna? (t. XIII, f. a) are rather large and 

 long, and armed at extremity with four short spines. They 

 spring from a knob or eminence projecting a little out 

 from the edge of the shell. The inferior antennae or rami 

 are large (f. b). The basal joint is very stout and rounded, 

 more than a third the length of the whole organ, and 

 furnished with three short spines on anterior extremity. 

 The two branches are rather short, compared with the 

 size of the basal joint and the size of the animal. The 

 external branch is divided into three articulations. The 

 first, or lowest, is very short, and has a small spine at 

 the outer angle ; the two others are nearly of equal lengtli. 



