ON A NEW HISTRIOBDELLID. 323 



posterior portion of the organ extends nearly to the posterior 

 end of the body. The ducts would appear^ however, to be 

 widely different. From each female aperture there runs a 

 very short canal opening into an ampulla, the cavity of which 

 is drawn out into digitations. This often contains a granular 

 material, which passes out and spreads over the surface for 

 some distance around the reproductive aperture. Usually one 

 only of the digitations communicates with another ventrally 

 placed vesicle of spherical form, containing bodies supposed 

 to be sperms. This vesicle communicates by a constricted 

 portion with a flattened canal, having cellular walls ciliated on 

 the dorsal side only ; this opens into the body-cavity. 



Living sperms were found in abundance in the body- 

 cavities of several females. In one instance they had pene- 

 trated in large numbers into the head, the coelom of which 

 is not completely cut off from that of the trunk. In one 

 instance they were found in the tail region — the partition 

 between this and the segmeut in front apparently not being 

 sufficiently complete to prevent their passage. 



In several specimens dense masses of sperms were found, 

 always in the neigbourhood of the ripe ovum. But it was 

 only in one specimen that I happened to meet with the 

 appearances represented in fig. 12, which appear to explain 

 the mode of impregnation. Here a darkish body {spr.), 

 having the size and shape of a cast of the internal cavity of the 

 penis, with short prolongations representing the three basal 

 processes, was found with its point directed inwards, close 

 to the single large ovum and close to the internal opening 

 of the oviduct. Close to it in front, in the next section, is a 

 mass of sperms which had begun to become scattered. Ob- 

 viously the foreign body is the case of a spermatophore, 

 thrown off from the inner lining of the penis. After having 

 been discharged — the penis having previously been thrust 

 through the body-wall — the spermatophore had become rup- 

 tured and its contents liberated. In the other specimens in 

 which sperms were found in masses, the case of the spermato- 

 phore had apparently become absorbed. 



