

AMPHIPODA OF SOUTHERN NEW ENGLAND. 467 



OO. Last three segments of the abdomen without fascicles of spines, although there 

 may bo Bpiniform projections Erom the posterior margins of the segments. 

 Terminal uropods with comparatively short and broad rami. 



Posterior perseopods stout Elasmopus, p. 507 



Terminal uropods elongated; posterior peraeopods rather slender M.f.ra, p. 525 



LL. Not with all the characters of L. 



M. Body spiny; secondary flagellum minute Rhachotropis, p. 493 



MM. Not as above. 



Coxal plates enormously developed: body tumid; no mandibular palp.. STEGOCEPH ALUs, p. 4s^ 

 Mandibles with palp; fourth abdominal segment with an upturned process; eoxal 



plates of ordinary size Pontoporeia, p. 17ti 



KK. First antenna 1 with no secondary flagellum. 

 L. Maxillipeds with the palp small and two-jointed: parasitic: thorax rather broad and 



tumid Lafystius, p. 192 



LL. Not as above. 

 M. Telson cleft. 



N. First gnathopods rudimentary Batea, 499 



NN. First gnathopods not rudimentary. 

 O. First three pairs of coxal plates pointed below; body with prominent spines or tuber- 

 cles and a median dorsal crest; head with a very prominent rostrum. 



Body with prominent tubercles on either side of the dorsal crest Epimeria, p. 491 



OO. First three coxal plates not pointed below. 



Fourth abdominal segment with a posterior dorsal prominence; no mandibular 



palp Dexamine, p. 498 



Fourth abdominal segment without a posterior dorsal prominence; mandibular 



palp three-jointed Ponti igen eia, p. 476 



MM. Telson not cleft. 

 N. Body dorsally carinated. 

 O. Abdomen with tubercles or spines on either side of the dorsal carina. 

 P. Postero- lateral margins of the abdominal segments with very large 



spines -. , Acanthozone, p. 491 



PP. Postero- lateral margins of the abdominal segments with tubercles but no large 



spines Plecstes, p. 488 



OO. Abdomen devoid of tubercles or spims. except at the postero-dorsal and postero- 

 lateral angles Paramphithoe, p. 489 



NN. Body without a prominent dorsal carina. 

 O. Antenn;e with calceoli; last peduncular joint of the first antenme with a terminal 

 lobe. 



Dorsal spines on some of the body segments Halirages, p. t '.<-"> 



No dorsal spines , Calliopius, p. 494 



OO. Antenna* without calceoli; no terminal lobe on the last peduncular joint of the 

 first antenna-. 



First antennae longer than the second Sympleustes, p 190 



First aiitenn;e shorter than the second iPHERUSA, p. 495 



GGG. Terminal uropods biramous, inner ramus minute. Last three segments of the abdomen fused. 



Uropods remarkably modified ...Chelira, p. 508 



CC. First two pairs of peneopods with spinning glands. 

 D. Terminal uropods uniramous. 



E. Mandibular palp one-jointed SiPHONffiCETES, p. r v_!J 



EE. Mandibular palp two-jointed Corophium, p. 521 



FEE. Mandibular palp three-jointed 



Last two pairs of uropods uniramous ; Cera pus, p. 517 



Penultimate pair of uropods biramous. Second gnathopods larger than the first ERICHTHONIUS, p. 518 



DD. Terminal uropods biramous. 



E. Propodusof the second gnathopods not subchelate Ptilocheirus, p. 522 



EE. Propodus of the second gnathopods chelate or subchelate, 

 F. Terminal uropods with shorl hooked rami (Podoceridae). 

 G. First antenna- with a secondary flagellum. 

 H. Hand mi thesecond gnathopodof the male very large, and having a thumb-like process arising 



from near the base of the posterior side - Jassa, p. Ml 



HH. Second gnathopods of the male not as in Jassa. 



Antenna' rather stoul, densely sctiferous posteriorly, flagella with few segments.. .Ischyrocerus, p. 513 



Antennce slender, with mul Particulate flagella Grubia, p. 510 



GG First antennae wit lion t secondary flagellum Amphithoe, p. 509 



FF. Terminal uropods with narrow rami devoid of terminal books. 

 G. Second gnathopods much larger than the first : first antennsewitb.no accessory flagellum.. Potjoceropsis, p. 524 

 GG. First gnathopods much larger than'the recond, first antenna- with a secondary flagellum. 



Second gnathopods of the male complexly subchelate Micro dedtopus, p. 514 



Second gnathopods of the male simply subchelate AUTONOfi, p. 516 



