1 86 REPORT OF NEW JERSEY STATE MUSEUM. 



and subcheliform, as a rule much more strongly built in male 

 than in female. Perseopoda more or less slender, three posterior 

 pairs generally increasing in length, and have basal joint laminar. 

 Last pair of uropoda, as a rule, projecting beyond others, and 

 with rami more or less foliaceous. Telson generally small, 

 lamellar, more or less deeply cleft. 



Genera numerous, and representing the typical development 

 of the Amphipoda. 



Key to the genera. 



a. Inner ramus of terminal uropods scale-like, rudimentary. melita 



aa. Inner ramus of terminal uropods not rudimentary, although often smaller 

 than outer. 

 h. Last three segments of abdomen with fascicles of spines. 



c. Abdomen carinated dorsally. carinogammarus 



cc. Abdomen not carinated dorsally, last three segments not produced 



behind into teeth. gammarus 



bb. Last three segments of abdomen without fascicles of spines, although 



spiniform projections from hind margins of segments may be present. 



ELASMOPUS 



Genus MELITA Leach. 



Melita Leach, Edinburgh Encyclop., VII, 1813, p. 403. Type Cancer Gam- 

 iiianis palmeta Montagu monotypic\ (Not consulted.) 



Ccradocus A. Costa, Rend, della Soc. Reale Borbonica, II, 1853, p. 170 (173). 

 Type Ceradocus orchestiipcs A. Costa, monotypic. 



Body more or less slender, with segments of mesosome always 

 evenly rounded above, those of metasome and urosome some- 

 times produced dorsally to dentiform projections. Cephalon 

 without any distinct rostrum, lateral corners rounded. Coxal 

 plates of moderate size, fourth pair largest, and more or 

 less emarginated posteriorly. Eyes distinct, though rather 

 small. Antennse of very same structure in two sexes, anterior 

 ones very slender and much longer than inferior, accessory ap- 

 pendage more or less developed. Oral parts normal. Gnatho- 

 poda rather unequal, anterior ones comparatively small and 

 alike in two sexes, and posterior ones much larger, in male often 

 enormously developed, and approaching sometimes to cheliform 



^ Leach, 1. c. Am. Ed., VII, 1815, p. 272. 



