1889.] OS SOME FRESHWATER OSTRACODA AND COPEPODA. 19 



by an opaque filamentous mass, which on closer examination is found 

 to consist entirely of innumerable intertwined spermatozoa. These 

 sacs — representing of course the seminal receptacles — form 

 posteriorly, above the insertion of the caudal rami, a sharp bend, 

 and their narrow, neck-shaped outer part would seem to join 

 the above mentioned canal curled up within each of the ge- 

 nital lobes. 



The inner genital organs of the male exhibit a very com- 

 plicated aud remarkable structure (see PI. IV, figs 1 & 2). The 

 testes, as the ovaries, are wholly received between the lamellae 

 of the valves, but instead of forming a single pair of saccular 

 organs, they consist on either side of no less than 5 elongate 

 and narrow band-like appendages, 4 of which form a dense 

 bundle curled up in the posterior part of the valve, with their 

 narrow tapered extremities reflexed along the dorsal margin, 

 whereas the fifth pair, somewhat differing in structure from the 

 others, take a forward direction, running along the anterior and 

 inferior edge. All the 5 appendages converge at the base on 

 either side to a point just above the great adductor of the shell 

 and the 4 posterior appendages are here found to coalesce to a 

 single stem penetrating the walls of the body. The appendages 

 are generally found filled up with numerous extremely fine thread- 

 like bodies, more frequently curled up pretly regularly in loose 

 spiral bends or skrew-like turns. Besides there are present a 

 more or less considerable number of large nuclear cells, more 

 especially accumulated in their terminal part, and in younger 

 specimens even wholly occupying its lumen (see fig. 10). ( These 

 cells (fig. li) are the germinal cells, or spermatocysts, fr om w hic h 

 the spermatozoa develop. The latter, highly distinguished! by 

 their comparatively enormous size and highly complicated struc- 

 ture, are successively poured off into the body-cavity, t which at 

 last becomes filled up with great masses of these filiform bodies, 

 apparently disposed without any perceptible ordre and curled up 

 in different manners (see fig. 1). The Finnish naturalist, Mr. 

 Nordqvist, which recently has published a most elaborate memoir 



