THE MALAYAN SPECIES OF ONYCHOPHORA. 51 



rudiments of tlie appendages^ tlie nervous system, and the 

 ventral organs. The upper moiety represents the rudiments 

 of the appendages, while the lower one, later on in the 

 development, splits into an inner and an outer portion, the 

 forerunners respectively of the nervous system and ventral 

 organs. In the region in front of the anterior portion of the 

 blastopore, the ectodermal thickening is continuous across 

 the middle line (PI. 6, figs. 10 a, 10 &, and 10 c) ; but in the 

 mid-region of the body, that is in the region where the 

 blastopore has been obliterated, the two thickenings are 

 Avidely separated from each other (PI. 6, figs. 10 d, 10 e, and 

 10/) ; while behind the blastopore in the region of the primi- 

 tive streak they converge and fuse together (PI. 6, fig. lOy), 



The disposition of these ectodermal bands presents another 

 feature in which the development of Eoperipatus ap- 

 proaches that of P. nov8e-zealandi8e(6). 



The mesodermal bands, which originate from the triangu- 

 lar-shaped thickenings noticed in surface view, and situated 

 immediately behind the blastopore, are placed exactly under 

 the ectodermal bands above described (PI. 6, figs. 10 a — J). 

 At the sides they are broken up into several somites, which 

 decrease in size from before backwards. In the anterior 

 region, in which the ccelomic cavity has already appeared, 

 every successive somite overlaps the one in front of it (PI. 6, 

 figs. 10 c, 10 d, and 10 e). The first somite has a well- 

 developed coelom, and is situated in the latero-ventral aspect 

 of the cephalic lobes (PI. 6, figs. 10 a, 10 h, and 10 c). The 

 second somite is considerably smaller and overlaps the first 

 one (PI. 6, fig. 10 c). The third somite is slightly smaller 

 than the second and passes forwards above it (PI. 6, fig. 10 e). 

 The same is true of the fourth and fifth somites, the remain- 

 ing ones being so small in size as to be incapable of over- 

 lapping (PI. G, fig. 10 g). 



As soon as the coelom begins to form the two walls of 

 the somite present distinctive characters. In the splanchnic 

 wall the nuclei are placed at a distance from one another, 

 and are flattened in the tangential plane ; but in the somatic 



