68 BRITISH COPEPODA. 



Genus 17. DIOSAOCUS, Boeck (1872). 



Anterior antenna 8-jointed, the peduncle (first four 

 joints) very long, flagellum (last four joints) short. 

 Inner branch of the posterior antenna 1- or 2-jointed. 

 Mandible-palp simple, 2-jointed. Outer branch of the 

 first foot very short, 3-jointed ; inner branch 3-jointed, 

 first joint much elongated, second and third extremely 

 short ; second, third, and fourth pairs having both 

 branches 3-jointed, except that the inner branch of the 

 second pair in the male is 2-jointed ; ovisacs two. 



It is perhaps doubtful whether the characters of this 

 genus are such as to warrant its separation from 

 Dactylopus, the most important diagnostic marks being 

 the elongated peduncle of the upper antenna, the 

 1-branched mandible-palp, and the double ovisac. The 

 only British species is Diosaccus tetiuicornis, but M. 

 Boeck has described a second species from Norway, 

 under the name of D. abyssi. 



1. DIOSACCUS TENUICORNIS, Glaus. PI. LIX,figs. 12 16, 



and PI. LX, figs. 1418. 



Dactylopus tenuicornis, Glaus. Die frei-lebenden Copepoden, 

 p. 127, t. xvi, figs. 1723 (1863). Cope- 

 poden Fauna von Nizza, p. 28, t. iii, 

 figs. 1719 (1866). 



Nitdkra B. & B. Ann. and Mag. Nat Hist., 



ser. iv, vol. xii, p. 137 (1873). 



Body slender, elongated, head united with first thora- 

 cic segment, and produced into a long curved beak (PI. 



