STALK-EYED CRUSTACEA 423 



Group I. Aberrantia. 

 Group II. Normalia. 



Synopsis of the Groups. 



I. The abdomen is very large in proportion to the 

 rest of the body ; its segments do not overlap. — (Group 

 Abe7'7'a)itia.) 



II. The abdomen is in proportion with the rest of 

 the body, both being equally developed ; its segments 

 more or less overlap. — (Group Normalia.) 



Group I. Aberrantia (Spence Bate). 



Carapace short and compressed, with little or no 

 rostrum. Last thoracic segment articulated with the 

 preceding segment. The segments of the abdomen are 

 long, and do not overlap each other. Eyes small. 

 Antennae have long peduncles. The legs are more or 

 less armed with pincers ; first pair the longest, the 

 posterior pair more or less directed backwards. The 

 abdominal appendages are long and have two branches. 

 The swimminsf orean is stronsr. 



Family I. Callianassidae. 

 Family II. Thaumastochelidae. 



Synopsis of the Families. 



A. There is no scale on the base of the external 

 antennae. — {Calliaiiassidce.) 



B. There is a scale on the base of the external 

 an ten na;. — ( TJiaiiinastocJielidce^ 



