INTRODUCTION. 11 



pairs, hence the name of the Order, Decapoda.* The order 

 is divided into three suborders — Brachyura, Anomoura, and 

 Macroura — the characters of which will be found under 

 their respective heads. 



Suborder I. Bhachyura, Latr. 



In the species of this division the abdomen is very 

 slightly developed, and not employed to assist the animal 

 in swimming ; it is folded under the body, and has no 

 traces of appendages on the segment which precedes 

 the last. The sternal plate is rather wide between all the 

 legs, and is never linear : the surface of the carapace 

 generally divided by grooves, for the most part correspond- 

 ing with the muscular insertions, and which circumscribe 

 regions of the stomach, heart, genital organs, branchiae, 

 etc. The abdomen is generally very much wider in the 

 females than in the males : in the latter it is more or less 

 triangular, while in the former it is oval. 



Tribe 1. OXYRHYNCHITA, M. Edw. 

 Carapace contracted in front ; front part projecting, and 

 forming generally a very prominent beak.f Mouth ap- 



* Ae/ca, ten ; irovs, irohos, a foot. 



t "Whence the name, — o|uy, sharp ; pvyxos, a beak. 



