THE MALAYAN SPECIES OF ONYCHOPHORA. 61 



nothing that would tend to make it necessary even to modify 

 not to speak of abandoning, the view that the renal duct is 

 almost exclusively mesodermal; that is, that the ectodermal 

 portion is extremely short, though always present — a con- 

 clusion arrived at from the histology of the fully developed 

 organ. 



It will be observed that the above description of the de- 

 velopment of the coelom in Eoperipatus agrees with that 

 given by Mr. Sedgwick of the processes occurring in P. 

 cap en sis, save in a few details of no material importance, a 

 confirmation which bears weighty testimony to the correct- 

 ness of that embryologist's work. This correspondence in 

 the development of the coelom in these forms goes far to 

 prove that the changes which take place in P. edwardsii 

 would be found to agree, if only they were properly exa- 

 mined; for P. edwardsii and Eoperipatus are much more 

 closely related to each other than either of them is to P. 

 capensis. 



(2) The Development and Disappearance of the 

 First Somite {som.^). 



The early stages in the development of this somite have 

 been already described, and are illustrated on PI. 6, figs. 

 9 c, 10 a, and 10 6. In fig. 11a on PI. 7 it is represented at 

 the zenith of its development, but still undivided. At the 

 side of the stomodseal invagination, its inner wall, contrary 

 to what occurs in the somites situated behind, has consider- 

 ably thickened to produce the rudiment of the mesodermal 

 portion of the fore-gut. In figs. 12 a, 12 6, 12 c, 12 d, and 12 e, 

 on PI. 7, the first somite is shown in its divided condition, the 

 two portious being separated by a thin septum, which was 

 probably produced in the manner described by Mr. Sedgwick 

 as occurring in all the somites ; but I have no evidence on this 

 point. The two portions into which the somite is divided 

 extend the whole length of the rudimentary antenna (PI. 7, 

 fig. 12 a, som.^). Posteriorly they pass backwards almost to 

 the level of the second pair of rudimentary appendages. 



