W. H. Leigh-Sharpe 
287 
the side of the bursa again runs ventrally forwards well into the pre- 
clitellum, such an anterior position being somewhat unusual in my 
experience. Next it turns back completely, running in a posterior direc¬ 
tion dorsally, at the same time widening out to form a muscular ductus 
ejaculatorius. This is best seen in lateral view (Fig. 8 c). The ductus 
ejaculatorii stretch forward to the anterior border of the clitellum (being 
themselves in the preclitellum when unextruded), and may be practically 
said to unite together before entering the bursa by a common opening, 
so that the common end piece is practically nil, and not as in Calliobdella 
lo'phii. 
The bursa is insignificant, as regards saccular development, but as 
usual the whole bursa can be everted, and forms a penis capable of 
Pig. 10. Platybddla anarrhichae. Transverse section of the animal in the clitellar region. 
St. stomach; d.s. dorsal sinus; n.g. ganglion on ventral nerve cord; d.e. ductus 
ejaculatorii; c.v. coiled part of vas deferens; v.d. forward-going portion of vas 
deferens; p. penis; x. body wall as in Pig. 2 but without cocoon gland cells. 
standing out a considerable distance from the body. The penis 
(Fig. 8 b) includes the ductus ejaculatorii in about half its length. 
A comparison of the relative sizes of the genital apertures in Fig. 7 
and of the penis and $ genital aperture in Fig. 8 A and b, can only lead 
to the conclusion that it is impossible, on account of its size, that the 
penis should enter the ? opening. Rather it appears that the penis must 
be an organ of attachment only (hence perhaps the powerfully muscular 
ductus ejaculatorii for driving the semen out) after the fashion of that 
met with in the Mollusca, but hollow. The aperture at the tip of the penis 
is rather well adapted to surround the $ aperture which is papillate. 
There are no vesiculae seminales in the sense in which this term is 
used in Calliobdella lophii. 
