DEVELOPMENT OF PERIPATUS CAPENSIS. 
769 
passes back on the other side, up the body again a short distance, and then turns down 
again, forming a loop to reach the male generative opening, which lies in the same 
position as that of the female. The duct thus passes under one of the ventral cords 
again. The lower part of the duct, from the loop downwards, is enlarged, muscular, 
and supplied much more richly than the remainder with trachese. It is therefore au 
ejactulatory duct, and perhaps is somewhat exerted in copulation as a penis. In only 
two specimens of males were the terminal ducts dissected out with care. In one case 
the terminal duct was that from the right testis, in the other that from the left. The 
vas deferens of the other testis of the pair, after leaving its vesicula seminalis, becomes 
twisted up with the spiral coil of the testis of the other side, and after coiling about in 
the lower part of the body-cavity like its fellow, passes to that side of the terminal loop 
of its fellow duct which is opposite to that which is enlarged into the penis-like organ, 
and is there bent itself into a sharp loop, which is closely applied against the side of 
the large terminal loop and fused to it, the two ducts here anastomosing. This 
arrangement was observed to be exactly similar in both the dissections made, though 
the sides were reversed. The enlarged part of the duct or penis (p) appears, as 
described, to be a continuation of one of the ducts only, the other duct being cut short 
and entering from the side. But from the way in 
which one duct passes under the nerve-cord and not 
the other, and from the curious sharply turned loop 
formed by this latter duct on entering its fellow, it 
would appear that the original condition had been 
almost exactly similar to that existing in the female 
organs. A common duct (now the lateral penis) lay 
in the middle line on the inner surface of the ventral 
wall of the body, the tube being much longer in the 
male than in the female. The two vasa deferentia 
passed inwards, one on each side under the nerve- 
cords, to enter the common median tube together at 
its upper extremity, as do the oviducts in the female. 
The common duct, however, in the male has become 
longer and longer, and thus formed an upward loop in the body, which looping has 
necessarily brought about the sharp turn in the one vas deferens ; the large loop at 
the same time slipped out sideways under the nerve-cord, and lay in future always on 
the side of the body ; and the other vas deferens following it was dragged under the 
second nerve-cord, and thus now passes in the present singular manner under both 
nerve-cords. The diagrammatic woodcut may serve to make this plain: — VC 1 , VC 
are the ventral nerve-cords, P the penis or enlarged common terminal duct. The right 
vas deferens (Pd) passes right across the body at its very end under the ventral 
cords, and, turning up, is apparently continued in a sweeping curve into the 
penis. The left vas deferens ( Ld ) enters the loop of the penis with its peculiar sharp 
5 l 2 
