88 TBANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



The genital tube of the male, though being exactly as 

 long as the intestine, does not reach as far as the oeso- 

 phagus, because one-sixth is reflexed; it shows its greatest 

 width just in the middle, measuring here two-thirds of 

 the body-diameter, and thence it narrows gradually 

 towards the anus. The spermatozoa are spherical cor- 

 puscles, having a diameter of 7*3 — 8" 7 /*, and enclosing a 

 nucleus. The spicula are 42 or 43 /* long, accordingly a 

 little longer than the tail; they are entirely separated 

 from one another, not coalescent, and their proximal ends 

 are characteristically capitate; they appear slightly arcuate, 

 and terminate in an acute point. The accessory piece, 

 12" 5 /^ long, measures scarcely one-third of the length of 

 the spicula ; it is silicate or horse-shoe like, the opening of 

 which is directed towards the anus, i.e., outward, whereas 

 at the proximal end the two parallel lateral pieces are 

 united in an arcuate line ; these lateral pieces are slightly 

 thickened towards their distal extremities. 



Bhabditis oxycerca is chiefly characterised by the 

 structure of the bursa. In my opinion the bursa of 

 this species (PI. IV, fig. 3 c and PL Y, fig. 3 d) is formed 

 by the middle layer of the cuticula, described above, 

 being locally thickened on the tail, consequently not 

 by lateral wings of the cuticula ; this thickened layer 

 expands also, namely, over the sub-ventral and sub-dorsal 

 sides of the tail of the male. The tail, nevertheless, is 

 not completely enveloped by the bursa, but a short, 

 pointed terminal part projects beyond it, remaining free ; 

 this free portion is about half as long as the enveloped 

 part of the tail. The bursa is supported by eight papillce, 

 the distribution of which is highly characteristic and 

 exceptional. Six papilhe are situated on the ventral 

 surface of the bursa, at some distance from the ventral 

 median line ; these papillae are consequently sub-ventral. 



