4 STALK-EYED CRUSTACEA 



is distinctly defined in front. The first pair of legs only- 

 have pincers, although the others are sometimes formed 

 for holding ; the last pair are sometimes formed for 

 swimming, or may be little developed. 



Tribe I. Oxyrhyncha 



Tribe II. Cyclometopa. 



Tribe III. Catometopa. 



Tribe IV. Oxystomata. 



Synopsis of the Tribes. 



I. The canal from the branchial cavity opens at the 

 sides of the palate. The buccal cavity, quadrilateral, is 

 wide in front and long from before backwards. The genital 

 orifice of the male is hollowed in the basal joint of the 

 last pair of legs, and is not continued in a transverse 

 canal of the sternum. The gills to the number of nine 

 almost fill the branchial cavity. 



A. The space in front of the mouth is almost as long 

 as the buccal cavity. 



a. The carapace is pear-shaped, narrowed in front, 

 where it is usually produced into a rostrum. Orbits 

 directed outwards. — {Oxyrhyncha.) 



B. The space in front of the mouth is very short ; 

 wider than long. 



b. The carapace is wide and regularly bowed in front ; 

 not produced inito a rostrum. Orbits directed forwards. — 

 {Cyclometopa) 



II. The canal from the branchial cavity opens at the 

 sides of the palate. The buccal cavity, quadrilateral, is 

 wide in front, and long from before backwards. The 

 genital appendages of the male are either inserted in 



