THE CRUSTACEA OF XEW JERSEY. 167 



Key to the tribes. 



a. Abdomen rudimentary ; first thoracic segment fused with head ; forms 



of aberrant structure. caprellidea 



aa. Abdomen well developed ; head and eyes generally not of unusual size ; 



maxillipeds with palps. gammaridea 



Tribe Caprellidea. 



Head fused witli first segment of thorax. Abdomen rudi- 

 mentary. Second gnathopods larger than first. Usually gills 

 present only on third and fourth segments of thorax. Anterior 

 pairs of perreopods usually wanting. No pleopods. Uropods 

 rudimentary or wanting. 



Family CAPRELLID.E. 



TJie Skeleton Shrimps. 



Body narrow, cylindric. very flexible, last segment of meso- 

 some generally defined from cephalon by slight dorsal depres- 

 sion, third and fourth segments in female much broader than 

 in male, and carrying marsupial pouch. Superior antennae slen- 

 der and elongated, with multiarticulate flagellum. Inferior an- 

 tennae well developed, though usually much smaller than superior. 

 Buccal area rather prominent. Anterior lip broad, bilobed. 

 Posterior lip with distinct inner lobes. ^landibles with or 

 without palps. First pair of maxillae without any basal 

 lobe, palp well developed, biarticulate. and second pair small. 

 Maxillipeds normally developed, with large pediform palps. 

 Gnathopoda very unequal, anterior comparatively small and 

 originating far in front, beneath cephalon, and posterior much 

 larger and often very differently shaped in both sexes. 

 Peraeopoda more or less reduced in number, two iX)sterior pairs 

 always strongly developed and prehensile. Metasome and uro- 

 some forming together generally very small nodiform appendage 

 issuing between bases of last pair of peraeopoda. and carrying 

 more or less distinct rudiments of limljs (uropoda). 



