117 



plexing similarity both in its general appearance and in its behaviour. I very 



soon however became convinced of the fundamental difference of these 2 forms. 



Distribution. Sweden (Aim), British Isles (Brady), Germany (G. W. Muller). 



Gen. 20. Cypricercus, G. O. Sars, 1895. 



Generic Characters. Shell tumid, of more or less elliptical shape, higher 

 in front than behind, with the left valve overlapping the right more or less 

 conspicuously along the anterior extremity. Antennae well adapted for swimming, 

 the posterior ones unusually slender and attenuated. Mandibles normal. Max- 

 illae with both the palp and the masticatory lobes narrowly produced. Max- 

 illipeds with the vibratory plate well developped, palp in female of the usual 

 lash-shaped appearence; those in male slightly unequal. Anterior legs of 

 moderate length. Posterior legs with the terminal joint very small, apicale 

 bristle unguiform curved. Caudal rami long end slender, attached to the body 

 by a very mobile jointing. Copulative appendages of male terminating in 2 

 unequal lappets, the lower rounded, the upper very prominent, beak-shaped. 

 Ejaculatory tubes slender, with numerous whorls of radiating spikes, proximal 

 extremity cup-shaped. Spermatic vessels forming within the anterior part of 

 each valve a dense spiral coil. 



Remarks. This genus was established by the present author in the year 

 1895, to include a South African species, C. cnneatus G. O. Sars, and was 

 chiefly characterised by the powerfully developed caudal rami and by the 

 peculiar arrangement of the spermatic vessels of the male. It is nearly allied to the 

 genus Strandesia of Glaus (Neocypris G. O. Sars), and indeed G. W. Muller has 

 combined the 2 into one, though in my opinion they ought to be kept apart. I 

 have felt justified to include in the present genus the 4 succeeding Norwegian 

 species, which by recent authors have been referred to the genus Eucypris. True, 

 one of the most characteristic feature of this genus, viz., the peculiar arrange- 

 ment of the spermatic vessels, has not been stated, because in none of them 

 as yet male specimens have been met with. But in a closely allied species 

 from Algeria I have succeeded in examining that sex, and have found the 

 above named character perfectly as in the type species. The remarkable 

 development of the caudal rami is in all of them in full accordance with 

 that in the South African species. 



