NOTES ON ACANTHODRILOID EARTHWORMS. 293 
externally on Somite xvii (fig. 8), by a separate pore from that 
of the prostate duct. Its wall is muscular, and its posterior 
extremity appears to be fixed to the body-wall by muscles. 
The sac contains four long, delicate penial chetz, of which 
two are much longer than the others (fig. 9). The longer 
cheetz are sharply bent near their free ends, and this bent part 
is gracefully curved to a very fine point (fig. 9, b.). The 
shorter chetz are not bent. The ends of all the chete are 
beset by numerous minute spines or asperities (fig. 10), and 
there appears to be a groove along one side, so that they are 
somewhat triangular in section. 
When the prostate is removed or turned aside the sperm- 
duct can be traced along the body-wall to its pore in Somite 
xviii (fig. 7). There is no trace of a prostate in Segment xrx. 
The microscopic structure of the prostate is similar to that in 
Acanthodrilus, Deinodrilus, and other genera. The wall 
is formed of pyriform “ clitellar” cells, amongst which a few 
blood-vessels occur. The whole is surrounded by a flat coelomic 
epithelium (fig. 11, a). The penial duct is lined by short 
columnar cells, surrounded by a very thick muscular coat (fig. 
12), around which are blood-vessels and ccelomic epithelium. 
There is only one pair of spermathece in Somite vi1t; at first 
sight, however, there appears to be two pairs of these organs 
(fig. 3) ; but the structures lying in Somite vir are in reality 
the appendices or diverticula of the spermathece, so common 
amongst earthworms. Mr. Beddard has already remarked upon 
the large size of the diverticulum in this species. On one side 
it is actually larger than the body of the spermatheca itself. 
The spermatheca (fig. 13, s) is ovoid, with rather a thick 
wall, as can be seen in the left sac in fig. 3, where its dorsal 
wall has been removed. The sac communicates with the 
exterior by a short, thick, muscular duct, which resembles 
in its structure that of the prostate. This duct opens in the 
anterior region of the segment, and is joined close to the body- 
wall by the diverticulum. This is a sac of smaller or larger 
size than the main sac, roughly cylindrical and truncated, and 
contains spermatozoa. 
