528 RICHARD I5VANS. 



primitive structure. The greater number of denticles in the 

 outer blade of the jaws of P. tuberculatus seems the more 

 primitive, but of the inner blades those of the Malay species, 

 containing in all a greater number of denticles, seem to 

 approach nearer the original arrangement. In the position 

 of the renal papillae of the fourth and fifth pairs of legs, the 

 arrangement occurring in Eoperipatus is decidedly the 

 more primitive, and in the structure of the ovai'y and the ova, 

 9,8 well as in their method of development, the condition 

 found in the Malay species is nearer the ancestral arrange- 

 ment than that found in the genus Peri pat us. 



In the same communication Bouvier says that it would be 

 possible to believe the species of Oceania to be derived from 

 those of Africa; but, seeing that they have some primitive 

 features, e. g. the position of the sexual orifice and of the 

 nephridial pores of the fourth and fifth pairs of legs, he says 

 that it may be supposed that the dispersal of the group took 

 place in both directions at the same time ; towards the east 

 in the case of Africa, and towards the west as regards 

 Australia and the adjacent region. In a later publication 

 Bouvier does not seem so definite in his opinion; for he uses 

 the word certain in his first paper (4), while in the second 

 he uses the word probably (3). Curiously enongh, the 

 description given by Bouvier of P, Tholloni in the paper in 

 which he argues the American origin of the Peripatidas is 

 exactly what was wanted to prove the possibility of the 

 origin of the Australian forms from Africa;. for it does away 

 with any force there may be in the argument based upon the 

 possession of primitive features by the latter. The prob- 

 ability of the African origin of the Australian forms is 

 strengthened by the discovery of the genus Opisthopatus 

 by Purcell — a genus which Bouvier himself has placed beside 

 the Australian genns Peripatoides because the genital 

 orifice is between the last pair of legs (5). When to all this 

 is added the argnmeut drawn from the primitive structure of 

 the Malay species, the view that the Peripatidas originated 

 in Central America and the Caribbean Region seems well- 

 nigh impossible. 



