DIAPTOMUS. 59 



branch much the smaller. Abdomen of the male 5-, of 

 the female 3-jointed. Eye situated in the median 

 line. 



1. DIAPTOMUS CASTOR, Jurine. PI. VI, figs. 6 13. 



Cyclops cceruleus, O. F. Miiller. Entomostraca, p. 102, t. xv, 

 figs. 19 (1785). 



lacinulatus ( ? ), Miiller. Ibid., p. 105, t. xvi, figs. 4 6 



(1785). 



rubens ($}, Miiller. Ibid., p. 104 t. xvi, figs. 13 (1785). 

 Monoculus Castor, Jurine. Histoire des Monocles que se trouvent 



aux Environs de Geneve, p. 50, tabs. 4 6, 



(1820). 

 Cyclopsina M. Edwards. Nat. Hist. Crust., vol. iii, 427 



(1840). 

 Diaptomm Castor, "Westwood. Partington's Cyclopaedia, art. 



"Cyclops "(1836). 



Baird. Nat. Hist. Brit. Entom., p. 219, 

 tab. xxvi, figs. 1, 2, 2 aj (1850). 



Glaus. Die freil-ebenden Copep., p. 201, 



t. xxxv, figs. 15 and 16 (1863). 



Lilljeborg. De Crust, ex. ord. trib., t. xii, fig. 



10, t.xiii,figs. 110, t. xiv, figs. 14 (1863). 



Lubbock. Trans. Linn. Soc. Lond., vol. xxiv, 



p. 197, pi. xxxi, figs. 711 (1853). 



Westwoodii, Lubbock. Loc. cit., pi. xxxi, figs. 1 6. 



Castor, Fric. Die Krustenthiere Bohmens, p. 225, fig. 22 



(1871). 



Anterior antenna (fig. 8) 25-jointed ; gradually 

 tapering from the base and beset with setse of mode- 

 rate length, one or two on each segment, except on 

 the terminal one, which has five at its extremity ; right 

 antenna of male (fig. 7) provided with a hinge-joint, 

 above which for the length of six segments it is much 

 swollen ; the 13th joint is armed with a strong mar- 

 ginal spine, and the 10th and llth with spines of a 

 similar kind though smaller ; the hinge is situated 



