NEW SPECIES OF OCNERODRILUS. 261 



vicinity of the male pore it narrows considerably, but 

 widens again nearer the pore. The interior lumen of the 

 muscular part is much wider close to the glandular part 

 of the prostate. The walls of the muscular part consist 

 of spirally wound muscles, which enclose a row of gland- 

 ular bodies arranged at intervals in globular masses around 

 the lumen (fig. 25). 



Spej-m ducts. The most important character of Oc- 

 iierodriltis Rosce is connected with the sperm ducts. In 

 all the others, except O. contractus and agi'icola, the two 

 ducts on either side unite in somite xii into one continuous 

 duct, of equal size and thickness throughout its course, 

 and even in the somite of the male pore (xvii) is in no 

 prominent way differentiated. But in Ocuerodrihis 

 Ros(B the sperm-tube is prominently modified in xvi 

 and xvii. It is there enlarged to about five or six times 

 its original or usual size, forming a kind of long, cylin- 

 drical, shuttle-like at both ends, tapering enlargement, 

 the lumen of which is somewhat wavy and as wide 

 as the sperm duct before it enters the enlargement. The 

 transition between the narrow and the wide part of the 

 duct is short, but gradual. Compared to the prostate 

 gland, this enlargement of the sperm duct is about one- 

 fourth wider than that organ at its widest point. It is flat 

 or compressed, and when in its natural state lies closely 

 pressed to the parietes of somites xvi and xvii, parallel 

 to the ventral ganglion. In length this enlargement 

 reaches from the middle of somite xvii to the anterior end 

 of somite xvi, thus occupying a length of almost, but not 

 entirely, one and one-half somite. The enlargement is 

 about one-third wider than the widest part of the ventral 

 ganglion in the same somite. 



The enlargement consists of a heavy longitudinal layer 

 of muscles, composed of small, shuttle-like cells, arranged 



