STALK-EYED CRUSTACEA 299 



mentary or very short ; last joint of walking legs very 

 short. Walking legs well developed. — (Subfamily Pin- 

 notherincB.) 



b^. Third joint of the external maxillipedes and last 

 joint of walking legs are distinctly developed. Last pair 

 of walking legs rudimental or wanting. — (Subfamily 77^,i-rt- 

 podincE^ 



B. Carapace convex, usually subglobose. 



b. Front rostrated ; rostrum deflexed. The external 

 maxillipedes bulge out beyond buccal cavity, and their 

 third and fourth joints are well developed. Last joint 

 of walking legs styliform and well developed. — (Sub- 

 family MyctirmcB.) 



C. Carapace flattened, more or less triangulate. 



c. Front rostrated. Third joint of the external maxil- 

 lipedes and last joint of walking legs well developed. — 

 (Subfamily Hymenosojnince.) 



Tribe IV. Oxystomata. 



Oxystomata Miers. 



Orbiadata Latreille. 



Oxystovies H. Milne Edwards. 



Leacosoidca vel Oxystomata . Dana. 



Carapace convex or depressed, transverse, with the 

 antero-lateral margins arcuate or orbiculate, or even 

 subglobose, or more or less oblong, with subparallel or 

 slightly convergent margins. Internal antennae longi- 

 tudinally or obliquely plicated. Epistome very much 

 reduced or rudimentary. Buccal cavity more or less 

 triangulate, nearly always produced and narrowed in 

 front, with the margins anteriorly convergent. The 

 afferent channels to the branchiae enter either behind 



