306 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The sterna of the last four thoracic somites arc 

 characterised by a median groove which marks the place 

 at which the " Median plate " of the endophraginal system 

 has grown inwards. The anterior end of this median 

 groove is marked by a very deep depression which is 

 situated at the posterior end of the fourth thoracic 

 sternum. 



At the outer and posterior corners of each 

 sternum are backwardly directed areas — the " episterna " 



Fig. 3. — Ventral view of post-oral 

 cephalothoracic sterna (male). 



F.S. = Fused sterna of the two 

 post-oral cephalic and the first 

 three thoracic somites. 4.ts. — S.ts. 

 = Sterna of the 4th to 8th thoracic 

 somites. Ep.s. = Episternum. 

 P. = Sternal papilla of the 

 abdominal locking apparatus. 



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(Eps.) which run for a short distance alongside the 

 following sternum, from which they are separated by 

 distinct sutures. Between each episternum and the 

 corresponding sternum is a slight groove which is not very 

 distinct in the edible crab. In Portunus and other crabs, 

 however, this groove is much more distinct so as to 

 suggest a complete separation between the sternum and 

 episternum. This probably explains why Brooks* states 



Brooks, Handbook of Invertebrate Zoology. 



