10 



African species come free in the mixocoel, applying themselves 

 to the walls of it. 



As the cavity of the ovary is a part of the coelom, it is 

 obvioiis, that some of the sexual cells can be situated in the 

 inner walls of the ovaries, as it happens indeed in a few cases 

 nientioned above. 



The occurrence of perforations in the walls of the ovaries also 

 can easily be explained : they must be considered as the last 

 remnants of the Communications between the ovarian cavities and 

 the other part of the coelom. 



As most of the eggs arise in the ventral division of the coelom, 

 there seems to be no obvious reason for the separation of the 

 dorsal part to givc rise to the „ovary". This separation originally 

 must have had another purpose, which, I tliink, was to form 

 a cavity for receiving the sperma at the time, when the 

 Annelidan forefathers of the Onychophora assumed a terrestrial 

 life and in consequence of that got an internal fertilization. The 

 „ovaries" of the Onychophora thus originally had the function of 

 receptacula seminis and in Peripatoi^sis they have preserved this 

 function upto the present time. 



In other Onychophora, and perhaps in most species of Peripa- 

 topsis already, the eggs probably no Jonger fall into the mixo- 

 coel, but they reach the cavity of the ovaries directly through 

 the egg-stalk by a central hollow, arising in it. This simplifi- 

 cation seems to be induced by the increase of yolk, which pre- 

 vented the free locomotion of the eggs in the body cavity. The 

 most strongly modificated are the American species and the African 

 Mesoperipatus Tholloni Bouv., in which all eggs are endogenous 

 and can fall directly into the ovarian cavity. 



In tlie meantime the receptacula lost their original function and 

 new receptacula arose from parts of the oviducts. Such recepta- 

 cula, more or less developed, exist in all Onychophora, cxcept 

 Peripatopsis. 



The agreement existing in the metliod of egg-formation be- 

 tween Peripatopsis Deiraali and Annelida, as hcre described, does 



