STALK-EYED CRUSTACEA 479 



far as the rostral point. There are two keels upon the 

 sides of the carapace, each terminating in front in a spine. 

 The eyes are large, and lodged at the base of the rostrum 

 in a fossa of the basal articulation of the internal antennae. 

 The basal scale of the external antennfe, instead of being 

 straight and spiniform as that of Oplophorus, is broad 

 and rounded in front ; the flagellum is fine and slightly 

 elongated. The legs of the first pair are the shortest of 

 all, but they are more stout ; those of the second pair are 

 more thin. All the legs have at their base an appendage. 

 The abdomen is strongly curved at the third segment; 

 it has a very prominent median keel that only commences 

 a short distance from its anterior edge ; it has towards 

 its posterior third a small tooth, and it terminates behind, 

 not in a large spine as Oplophorus and Heterocarpus, but in 

 two small symmetrical teeth. The fourth ring is feebly 

 keeled, and has three small teeth behind, one median, two 

 lateral. The fifth has but the two lateral. The other 

 segments are rounded above. 



I. Gonatonotus crassus, 



Gonatonotus crassus . . A. Milne Edwards. 



The same as the genus. 



Range. — Grenada; in deep water. 



Family III. Palsemonidae. 



Pahcnionidce . . . Spence Bate, Miers. 



Palceuionidci; (part) . Dana. 



Paleuwnieus^ , ^ ^^ ,^-, t- , 



, , , ' fpart) . H. Milne Edwards. 



Alphcens \ ^ ' 



Carapace dorsally rounded and laterally compressed. 

 Rostrum long, laterally compressed, and usually armed 

 with teeth. Abdomen laterally compressed ; the sides of 



