392 ARTHUR DENDY. 



to be exactly analogous to tlie blastodermic vesicle of 

 mammals." 



I am aware that tlie loss of yolk by the mammalian ovum 

 has been questioned, but it is possible to doubt anything, 

 and the subject need hardly be discussed in this place. 



The small number of legs in all the Australasian species — 

 smaller in 0. insiguis and 0. viridimaculatus than in 

 any other known species except the South African P. brevis 

 — might be used as an argument against their primitive 

 nature. Bouvier, indeed, maintains (1) with some reason 

 that the species with more numerous legs are more primitive 

 than those with a smaller number, and that "in many 

 respects the species belonging to Oceania [from Eastern 

 Australia to New Zealand] mark the present limit of the 

 evolution of the Onychophora." " In any case," he adds, 

 " it appears to be quite certain that Central America and 

 the Caribbean region have been the centre of origin and 

 migration of the species of Peripatus." 



Bouvier's knowledge of the Australasian species appears, 

 however, to have been limited. Thus he adheres^ to the 

 old idea of fifteen pairs of legs beiug cliaracteristic of the 

 " Oceanian " forms ; and, speaking of the jaws, he states that 

 '' here the accessory tooth disappears on the outer blade 

 also," as if this were a character of all the Australasian 

 species. He had, when he wrote, apparently never heard of 

 Peripatus Suteri, P. insignis, or P. oviparus, and in 

 another paper (3) he refers to P. no va3-zealandige as 

 having fourteen pairs of " jjattes." Nevertheless it is not 

 necessary at present to dispute Bouvier's general conclusions 

 as to the course of the evolution of the Onychophora, viz. 

 that as they spread from their original home in America, 

 " their limbs atrophied in succession posteriorly, and, at the 

 same time, their number became more and more constant. 

 The proximal spinulous arches followed, up to a certain 

 point, the same regressive course ; the nephridial papillge of 

 two pairs of limbs advanced by degrees towards the following 

 ' It must be remembered that tliis was written in 1900. 



