THE OVIDUCT. 97 



normal nephridia. The latter is merely a special portion of the 

 lateral portion of the somite, and does not seem to be re- 

 presented in the twenty-first somite. In the female of the 

 West Indian and South American species_, as described by 

 Gaflfron and Kennel, the case seems to be otherwise. Both 

 these observers have found between the ovary and recepta- 

 culum seminis a diverticulum of the oviduct, which ends in 

 a thin-walled vesicle. This structure is called " Ovarian- 

 trichter" by Gaffron, and "receptaculum ovorum" by Kennel; 

 and the latter observer distinctly states that he does not regard 

 it as homologous with the funnel of a nephridium (No. 31, 

 p. 66), apparently because of the thin- walled vesicle (of which 

 he was the discoverer) which closes up its free end. It seems 

 to me, however, that it is this very thin-walled vesicle which 

 renders it almost certain that the structure in question is 

 homologous with the so-called funnels of the normal nephridia, 

 all of which open into thin-walled vesicles of a nature pre- 

 cisely similar to the vesicle of the receptaculum ovorum. 

 Had the latter been absent and the diverticulum of the ovi- 

 duct opened directly into the body cavity, as Gaffron at first 

 supposed, then there would have been a very strong reason 

 against regarding the diverticulum as homologous with the 

 nephridial funnels. On my view, then, the receptaculum 

 ovorum would correspond to a nephridial vesicle which has 

 been drawn out of the leg portion of the body cavity and 

 placed in the central compartment. 



How comes it that this structure is absent from the oviduct 

 of the South African species ? In the neotropical species of 

 Peri pat us, in which the receptaculum ovorum is always 

 present, the generative ducts open between a pair of fully- 

 developed legs. In the South African Peripatus, on the other 

 hand, they never open between a pair of fully -developed legs, 

 but always behind the last pair of such ; the legs correspond- 

 ing to the generative nephridia being more or less completely 

 rudimentary (anal papillae, &c.); and it seems to me not un- 

 reasonable to suppose that this abortion of the appendage has 

 carried with it the abortion or non-development of the portion 



