THE PYCNOGONIDS. 27 



" No one affirms that the intestinal diverticula which now in 

 Phoxichilidium and Nymphon penetrate into the proboscis were 

 originally [ancestrally] in the palps and ovigerous legs. The 

 homology of the glandular organs of appendages II and III with 

 parts of the sexual organs is not based on any observation. . . . 

 But since I believe there are certain things which lessen Dohrn's 

 arguments in favor of the Annelid theory, I believe that at bottom 

 and the contents of pages 82-115 of his work confirms this 

 opinion, the ideas of this author and of mine upon the phylogeny 

 as well for the Crustacea as for the Pycnogonids are not very 

 different. At first I saw only the weak side of Dohrn's theory, 

 that he does not give any explanation of the almost universal 

 presence in the ontogeny of these animals of a characteristic larval 

 form (thelarval Protonymphon, which for myself is a true primary 

 larva in the sense of Balfour). So that I cannot adopt a theory 

 which causes to arise a form of Arthropods with many segments 

 from an Annelid with the same number of appendages ; but such 

 is not the opinion of Dohrn, as clearly expressed in the following 

 paragraph : ' Thus the larva of the greater part of the Pycno- 

 gonids may be regarded, with a grain of salt, as a form much 

 like the ancestor; but if, on the other hand, the absence of an 

 anal opening, the pincers of the first pair of appendages, the long 

 claws with their accessory spines, the structure of the proboscis 

 with its triturating apparatus and its ganglia, and the form of 

 the cutaneous glands with their integumentary hairs, can only 

 be considered as having been acquired in a much later stage, and 

 transmitted to larval life where they are found at present ; but 

 what remains in the larva that we may regard in reality as 

 inherited from its original condition ? Nothing but the nervous 

 system, i. e. the brain and ganglia, an intestine, three pairs of 

 appendages of a form modified according to circumstances, and 

 two eyes! But these are attributes which one finds equally in 

 the larva of Annelids with three segments ! And if then we take 

 into consideration that at one time the body of the Pycnogonids, 

 as we believe, showed a great uniformity in the segments (and 

 the generative organs prove this), that on the one hand there was 

 a concentration and a differentiation, and on the other hand 

 a reduction in number of segments, these two conclusions lead us 

 to admit a direct descent of the Pycnogonids from ancestral 



