514 ADAM SEDGWICK. 



median or generative portion, but remains in connection with 

 the latter and forms the channel by which the generative part 

 of the coelom communicates with the exterior. The generative 

 ducts are therefore modified nephridia, but it is important to 

 notice that the connection between these structures is not to be 

 compared with the so-called funnel of the normal nephridia. 

 The latter is merely a special portion of the nephridial or 

 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 

 Gaffron 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 Gaff'ron, 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. 14, 

 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 receptaculum ovorum. Had the latter 

 been absent and the diverticulum of the oviduct opened directly 

 into the body cavity, as Gafi'ron 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 had been drawn out of the leg 

 portion of the body cavity and placed in the central com- 

 partment. 



How comes it that this structure is absent from the oviduct 

 of the South African species ? In the neotropical species of 

 Peripatus, 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 



