ment of Nebalia is apparently identical with that of Oniscus, as 

 studied by Bobretzky, and probably all the Tetradecapods. and 

 also with that of perhaps the majority of the Decapods. As in 

 Oniscus the segmentation is partial, the blastodermic cells arising 

 from the subdivision of a polar cell, finally forming a blastodermic 



appendages arise ; these corresponding to the two pairs of an- 



men is distinct from the cephalothorax, but on the whole the em- 

 bryo may be said to pa>s through a naiiplius stage. 



mnltaneously, the abdomen increases considerably in length, when 

 the ten other pairs of foliaceous feet spring forth. Meanwhile 

 the bivalved carapace grows out from behind the eyes, covering 

 the cephalothorax and base of the abdomen. The young hatches 

 soon after the shield is developed and the further changes are but 

 slight. 



The Nebalia, then, in brief, passes through the following stages : 



1. Partial segmentation of the yolk. 



2. Nauplius stage (in the egg). 



3. Larval form like the adult ; with no metamorphosis. 



Development of the Tetrodempods. Much good work has been 

 done since the days of Rathke, on the mode of growth of the fresh 



