DAPHNIA. 
91 
Monoctjltjs, Bradley, Phil. Account of Works of Nat., 202, t. 25, f. 5. 
Le Ptjceron verdatre, Ledermuller, Mikroskop. Gemiiths. Augen- 
ergotz., 146, t. 75, f. 2. 
Var. a. Daphnia longispina, Muller, Entomost., 88, t. 12, f. 8-10. 
— Latreille, 1. c., iv, 226. 
— Bose, 1. c., ii, 283. 
— Bamdohr , Beyt. zur Naturg. ein. Deutsch. 
Monoc. arten, 24, t. 7. 
— Lamarck, 1. c., v. 127. 
— Straus, 1. c., t. 29, f. 23-4. 
— Besmarest, 1. c. 372. 
— M. Edwards, 1. c., iii, 380. 
— Koch, Deutsch. Crust., h. xxxv, t. 17. 
Monoculus longispinus, Fabricius, Ent. Syst., ii, 492. 
— Manuel, 1. c., 718, t. 265, f. 5-7. 
— Be Geer, 1. e., vii, 442, t. 27, f. 1-4. 
— Schceffer, Die grim. Arm-Polyp., 5 9, t. 2, f. 1 . 
Var. /3. Daphnia magna, Straus, 1. c., t. 29, f. 21-2. 
— Besmarest, 1. c., 373. 
— M. Edwards, 1. c., iii, 380. 
The shell or carapace is oval, quite transparent in 
general, and very finely striated on the anterior and 
middle portions of the valves, the striae crossing and inter- 
lacing with each other/ Sometimes it is of a red colour. 
The lower extremity of the valves terminates in a sharp 
spine, which is serrated on its edges. This spine varies 
in length ; in general, in the adult, being short and 
straight ; in some it is a prolongation of the dorsal 
margin, in others it is directly in the centre, but in the 
young, and in var. a, it is long, and slightly bent back- 
wards. The head is large, rounded on the upper and 
anterior portion, and produced lower down into a sharp, 
pointed beak. The superior antennae are exceedingly 
small, consisting of only a slight protuberance, and five 
or six short setae. The inferior antennae are very large. 
The anterior branch consists of four articulations, the first 
of which is very short. From the extremity of the third, 
issues a long filament ; and from the apex of the fourth, 
three others arise, of equal length. The posterior branch 
