134 U.S. NIATIONAL MUSEIUM BULLETEST 271 



lowing coxae, coxa 2 occasionally as small as coxa 1 but often as large 

 as coxa 3 and not hidden; coxae 3-4 enlarged, either overlapping or, 

 when immensely enlarged, with contiguous margins abutting; upper 

 lip usually deeply incised, rarely slightly excavate; mandible usually 

 with 3-articulate palp, rarely absent, molar well developed and trit- 

 urative or formed of a smooth protuberance or evanescent; lower 

 lips of two kinds (see figures); maxilla 1 with 1- or 2-articulate palp; 

 maxilla 2 rarely reduced in size, in one genus formed of a single plate; 

 maxillipeds normal; gnathopods of medium size or small, subchelate 

 or nearly simple, often incompletely carpochelate; uropod 2 shortened; 

 uropod 3 biramous, peduncle elongate (except Pseudamphilochus) ; 

 telson entire in all but one genus, often elongate and triangular, also 

 short and linguiform. 



Relationship. — The Pleustidae and Calliopiidae have large first 

 coxae, not hidden by following coxae. Leucothoidae have completely 

 carpochelate first gnathopods because article 6 is narrow\ 



The Stegocephalidae always lack a mandibular molar and palp; no 

 amphilochid lacks both at the same time; the mouthparts of stego- 

 cephalids project in a conical bundle, an accessory flagellum is present 

 and the first coxa is never hidden by the following coxae. 



The Stenothoidae, Thaumatelsonidae, and Cressidae have uni- 

 ramous third uropods. 



The Anamixidae have a completely carpochelate first gnathopod or 

 the appendage is absent, and a ventral cephalic keel replaces the 

 mandibles and maxillae. 



Pseudamphilochus Schellenberg is an aberrant amphilochid in its 

 normal coxa 1 and cleft telson. It tends to fall into the Eusiridae in 

 the various keys but a special place has been made for it also in 

 Gammaridea Family Key, Section G. It also appears to be a pleustid 

 with cleft telson even though its lower lip is not fully typical of 

 pleustids. It can also be confused with liljeborgiids even though the 

 accessory flagellum is absent in Pseudamphilochus. 



Incomplete carpochelation of gnathopods is ignored in the keys 

 and diagnoses to follow and the terms "simple" and "subchelate" 

 refer only to the condition of the propodus (article 6) . 



Neocyproidea peninsulae Hurley (1955) is removed to Peltopes. 



Key to the Genera of Amphilochidae 



1. Coxae 3-4 not immensely broadened, with contiguous margins overlapping, 



not concealing coxa 2 (fig. 59a) . . . (Amphilochinae, new subfamily) 2 



Coxae 3-4 immensely broadened, contiguous margins abutting, concealing 



the vestigial first two coxae (fig. 596) . (Cyproideinae, new subfamily) 10 



2. Mandibular molar large, with ridged and toothed triturating surface (fig. 



60c) 3 



