424 STALK-EYED CRUSTACEA 



Family I. Callianassidae. 



Callianassidce Spence Bate. 



The internal antennae have long flagella. The ex- 

 ternal antenncE have no scale at base. The first pair 

 of legs asymmetrical ; the right usually the largest, and 

 less perfectly chelate than the left ; the fifth joint on 

 the right side is formed, usually, as if it were a continua- 

 tion backwards of the hand — the sixth joint. The seg- 

 ments of the abdomen increase in size backwards, and 

 terminate in a foliaceous swimming organ ; second pair 

 of appendages is like the third and following pairs. 



Synopsis of the Genera. 



A. The external maxillipedes have their third and 

 fourth joint very broad. No spines on posterior margin 

 of swimming organ. — {Caliia?iassa.) 



B. The external maxillipedes have their joints more 

 or less rounded, pediform. There are strong spines on 

 the posterior margin of swimming organ. — {Cherajuus.) 



I. Callianassa. 



Callianassa . . . Leach, H. Milne Edwards, Bell, 



Spence Bate. 

 Cancer {Astaais) . Montague. 



Carapace ovate. The external maxillipedes have 

 their third and fourth joint very broad, constituting, when 

 in contact, a broad oval disc terminating in a small seta 

 formed of the last three joints. The posterior pair of legs 

 is minutely chelate. 



There are no spines on the posterior margin of the 

 swimming organ. The second pair of abdominal ap- 



