17 



that the episternum is anterior to the outer end of its own 

 sternum. He has evidently mistaken the groove mentioned 

 above for a true suture, and has therefore concluded that 

 the episternum belongs to the following sternum. The 

 last thoracic sternum has no episterna. 



At the anterior end of each episternum is a small 

 concavity into which fits the ventral hinge of the 

 coxopodite of the appendage of that somite. 



The sterna of the last two cephalic and the first four 

 thoracic somites (F.iS.) are fused together, without any 

 sign of separation into distinct segments as in the posterior 

 region of the thorax.t There is, however, a slight evidence 

 of a division in front of the fourth sternum of the thorax. 



That portion of the thoracic sterna which is covered 

 by the abdomen is characterised by the absence of setae. 

 There are long setae along the outer edges of the 

 episterna, and also on that portion of the fused sterna 

 belonging to the two last cephalic segments and the first 

 four thoracic segments. 



In front of the fourth thoracic sternum the outer 

 edges of the sterna are turned up vertically. 



The first post-oral cephalic sternum has two lateral 

 processes which project forwards and give support to the 

 Metastoma. The metastoma is a fleshy lobe forming the 

 posterior lip of the mouth. 



4. Cephalic epimera. 



In the first two cephalic somites it is difficult to 

 identify the epimera, but the latter are probably repre- 

 sented by the region between the outer portion of the 

 articular cavities of these somites and the carapace. 



t The two post-oral cephalic sterna, which are represented by two 

 narrow bars at the extreme anterior end of the fused post-oral sterna, 

 are separated from each other, however, by transverse sutures. 



