11 



sug-gest tlmt this species, and the genus Peripatopsis in general, 

 oan have preserved still other primitive qualities. The facts 

 mentioned thus strengthen the opinion of YoN Kennel (1. c.) 

 and WiLLEY '), who derive the Onychophora from forefathcrs, 

 possessing small eggs with little yolk, which were laid in 

 the water and from which were developed pelagic hxrvae. In 

 consequence of the transition to a terrestrial life one pair of 

 nephridia was transformod into uteri, in which now the develop- 

 nient of the Larvae took pLace. We thus have to look for points 

 of comparison between the embryo of the Onychophora and the 

 trochophora of Polychaeta and very suggestive is the hypothesis, 

 brought forward already by VoN Kennel, accordiug to wliich 



Diagrams of transverse sections of embryos of Farajjeripaius (A), Peripaiopsis (B) 

 aud Peripatus (C). The entoderm is repiesented by a dotted line. 



the embryonic membranes of Onychophores phylogenetically are 

 to be derived from the cephalic vesicle of the larvae of Polychaeta. 

 In this regard the species of Peripatopsis again, but also those 

 of Parapcripatus^ having generally a large „trophic vesicle" (see 

 fig. A), show a primitive condition. The cephalic vesicle, an ac- 

 commodation to the pelagic life, should have become supcrfluous 

 af ter the origin of viviparity, if it not had assumed another 

 function: the absorption of dissol ved food from the uterus, as 



1) Trophoblast and Serosa. A Contributioa to the Morphology of the Embryonic 

 Membranes of Insects. Quart. Jrn. of Mier. Sc., Vol. 41, 1S99. 



