82 STALK-EYED CRUSTACEA 



Synopsis of the Genera. 



A. Rostrum very short, its spines reduced to 

 tubercles. ^ ■ 



a. Basal ioint of external antennae with a fr^^, 

 very short spmc at its distal end. 



Tkoc. 

 a^. Walking legs compressed. — {Thoc.) 



B. Rostrum well developed, .short, or 

 ^^anting. ^ ^ ^ ^^-.£ 



Ik Basal joint of external antennae with ^ '^ 



a long spine or short spines at its distal Mithrax. 

 end. 



^'. Walking legs not compressed. — {Ulithra.v.) 



I. Thoe. 



Thoe . . . Bell, A. Milne Edwards. 



The carapace is slightly elongated, depressed, its 

 surface lobulated ; the interorbital region is wide. There 

 are no praeocular spines ; the superior orbital border 

 is unarmed. The rostrum is slightly advanced. The 

 basal joint of external antenna; is short and extremely 

 wide; the second joint is slightly flattened, and almost 

 reaches the extremity of the rostrum ; it is inserted in the 

 sides of the rostrum at a great distance from the orbit. 

 The external part of the fourth joint of the external 

 maxilHpedes is very wide in its middle portion. The first 

 pair of legs of the male is long and strong ; the hand is 

 compressed ; the fingers are excavated, when closed there 

 is a considerable space between them which varies with 

 age and sex. In the young and in females the fingers 

 are in contact through almost their entire length. The 

 walking legs are large ; the fourth joint has longitudinal 

 ridges ; the last joint is very small and has nodules. The 



