ON THE OVIPAROUS SPECIES OP ONYCHOPHORA. 389 



and chorion, may be either progressing towards a condition of 

 oviparity or away from it. Organs are not usually developed 

 ahead of their uses, and the chorion may be regarded as a 

 vestigial structm*e inherited from oviparous ancestors, in which 

 a chorion formed an essential protection to the deposited eg-g 

 during the lengthy period of development. In P. Leuckartii 

 and other viviparous species the chorion may have completely 

 disappeared. 



It is hardly likely that the oviparous habit should have 

 been independently acquired by two or more different species 

 in Australasia, but in no other part of the world. Yet, 

 unless we regard P. novas-zealandise as representing an 

 ancestral form of Ooperipatus, which is hardly admissible, 

 if only on account of the absence of the crural glands, this 

 is the conclusion to which we should be forced if we accept 

 the viviparous as being more primitive than the oviparous 

 habit. If, on the contrary, we regard the oviparous habit 

 as being the more primitive, it is not difficult to arrange the 

 Australasian Onychophora in a phylogenetic series, which may 

 bo tentatively represented as follows : 



r. Suteri P. novse-zealaiidise P. Leuckartii P. occideutalis 



Ooperipatus 



Of the three species of Ooperipatus, two (0. insignis and 

 O. viridimaculatus) are very nearly related to one another. 

 Each has only fourteen pairs of walking legs and no accessory 

 tooth on the outer blade of the jaw. 0. oviparus, on the 

 other hand, has fifteen pairs of walking legs and an accessory 

 tooth, and is evidently very closely related to the New South 

 Wales P. Leuckartii, though by no means far removed 

 systematically from its congeners. 



The occurrence of such closely allied species in Eastern 



VOL. 45, PART 3. — NEW SERIES. L» D 



