THE CRUSTACEA OF NEW JERSEY. 171 



Key to the faiiiilics. 



a. First antenn?e not shorter than second ; mandibles witli palps. 



b. Body more or less depressed, with posterior divisions poorly de- 

 veloped. COROI'HIID.ff 

 bb. Body slender, more or less compressed, with posterior divisions nor- 

 mally developed. 

 c. Cephalon not produced in front. 



(/. Perseopods without dactyls, but peculiarly modified for dig- 

 ging. POXTOPOREIID.E 

 dd. Perseopods with dactyls, not peculiarly modified. 



e. Rami of last pair of uropoda more or less foliaceous. 



GAMMARID^ 



ce. Rami of last pair of uropoda more or less conspicuously 

 hooked. podgcerid.^ 



cc. Cephalon produced in front to a defle.xed rostrum. ^ iphimEdid.^ 

 aa. Firi^t antennas shorter than second ; mandibles without palps. 



ORCHESTIID.E 



Family COROPHIID.E. 



Body smooth, depressed, metasome and iirosome compara- 

 tively poorly developed. Coxal plates very small, non-con- 

 tiguous. Cephalon broad, more or less produced in front, lateral 

 lobes small and narrow. Eyes, when present, placed within 

 lateral lobes of encephalon. Antenn?e more or less slender, in- 

 ferior ones usually more strongly built than superior, and ac- 

 cessory appendage of latter either present or wanting. Mandi- 

 bular palps well developed and triarticulate, or comparatively 

 small with smaller number of joints. Oral parts otherwise nor- 

 mal. Gnathopoda of different structure in various genera, gen- 

 erally rather unecjually developed. PenTopoda short and stout 

 or very nuich elongated. Last pair of uropoda small, uniramous. 

 Telson' usually lamellar and entire. 



Genera in moderate number. They are generally distinguished 

 by their depressed bod}- and poor development of posterior 

 regions. 



Key to the genera. 



ci. First two pairs of perjeopods with spinning-glands. 



/'. Mandibular palp three-jointed. cerapus 



bb. Mandibular palp two-jointed. Corophium 



(7(J. First two pairs of perseopods without spinning-glands. unciola 



