MOINA. 101 



1. MoiNA RKCTiRosTRis, Tab. XI, figs. 1, 2. 



Daphne kectirostris, Milller, Zool. Dan. Prod., 199, No. 2402, 1770. 

 Daphnia rectirostris, Midler, Entomost., t. 12, f. 1-2. 



— Z«?'m//e, Hist. Nat. Crust., iv, 22S. 



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



— Desmurest, Cous. geu. sur les Crust., 373. 



— Schrank, Eaun. Boic, iii, 206. 

 MoNOCULUS RECTIROSTRIS, Gmelin, Linu. Syst. Nat., 3000, No. 20. 



— Fubncius, Eutomol. Syst., ii, 493, No. 15. 



— Manuel, Euc. metb., 723, No. 19, t. 265, 



f. 10-12. 



— Jurine, Hist. Monoc, t. 13, f. 3, 4. 

 Pasithea rectirostris, Koch, Deutsch. Crust., li. xxxv, t. 24.* 

 Pasithea gibba (?), Koch, 1. c, li. xxxvi, t. 16. 



Daphnia macrocopus (?), Straus, Mem. Mus. Hist. Nat., v, t. 29, f. 30. 



The shell or carapace of this species is oval, transparent, 

 rounded at the back, and ciliated along the anterior margin. 



The head is erect, of considerable size, the inferior 

 extremity rounded, and furnished posteriorly with a very 

 slight spine, or tail. 



The antennules are of considerable size, of one joint, 

 flattened, and furnished at tlie extremity with tln-ee or 

 four short setse. The inferior antennae are very large, 

 the basal joint stout and fleshy, the branches long and 

 powerful, and the setae all finely plumose. 



The abdomen is emarginatecl at about half its length, 

 and terminates in two stout, curved spines. 



The male is smaller than the female, and is more slender 

 in form. The superior antennae are very long (t. XI, f. 1 a), 

 and apparently consist of two long, flat joints, the terminal 

 one having at the extremity a series of very small hooks. 

 When very young, the male has a long spine at the in- 

 ferior extremity of the carapace, and the head is much 

 more rounded. As moulting takes place, however, he 

 loses the spine, and the head becomes more elongated. 



Hah.— VowA upon Blackheath, October 1849. 



* Tlie genus Pasithea, having been used in zoology twice previously, cannot 

 be retained. 



