170 PROCEEDINGS OF THE NATIONAL MUSEUM vol, 117 



Uropod 2 small, uniramous, spatulate; telson small, entire; antenna 2, 

 peduncular segment 5 lobate behind; mandible without incisor. 



Neohaustorius, new genus. 14 



12. Peraeopod 5, coxal plate broadly acute or rounded behind, segment 6 



about equal to segment 5; uropod 1, posterior margin of peduncle apinose 



throughout; telson narrowly V -cleft, lobes rounded 13 



Peraeopod 5, posterior lobe of coxal plate sharply elongated, segment 6 

 markedly longer than segment 5; uropod 1, posterior margin of peduncle 

 centrally unarmed; telson very broad, shallowly V-cleft. 



Parahaustorius attenuatus, new species (p. 182) 



13. Peraeopod 5, segment 4 subrectangular, posterior margin subtruncate, 



with two (or three) prominent spines; peraeopod 4, segment 6 not longer 

 than segment 5; uropod 1, inter-ramal spines less than half inner ramus. 

 Parahaustorius holmesi, new species (p. 180) 

 Peraeopod 5, segment 4 narrowing behind, posterior margin oblique, with 

 one spine; peraeopod 4, segment 6 longer than segment 5; uropod 1, 

 inter-ramal spines more than half length of inner ramus. 



Parahaustorius longimerus, new species (p. 178) 



14. Antenna 2, flagellum abruptly narrowing beyond segment 1; uropod 1 



uniramous; maxilla 2, outer plate semilunate. 



Neohaustorius schmitzi, new species (p. 188) 



Antennae 2, flagellum gradually narrowing; uropod 1 unequally biramous, 



inner shorter (occasionally lacking) ; maxilla 2, outer plate broad, apically 



rounded Neohaustorius biarticulatus, new species (p. 186) 



15. Head broadest posteriorly, lateral margins subparallel, rostrum short; 



uropod 1, rami distally expanding, inner ramus the longer; uropod 3, 

 terminal segment of outer ramus small or vestigial; maxilla 2, outer plate 

 little larger than inner, weakly plumose; telson shallow-cleft, slender-setose. 



Pseudohaustorius, new genus. 16 



Head broadest medially, lateral margins convex, rostrum strong; uropod 1, 



rami distally tapering, outer ramus usually the longer; uropod 3, terminal 



segment of outer ramus normal, distinct; maxilla 2, outer plate very 



large, plumose; telson sharply cleft, short-spinose 18 



16. Peraeopod 5, coxal lobe not exceptionally elongate; hindlobes of segments 4 



and 5 lacking a distinct posterior border; hindmargin of telson nearly 



straight Pseudohaustorius borealis, new species (p. 193) 



Peraeopod 5, posterior coxal lobe large and elongate; hindlobes of segments 4 

 and 5 with distinct posterior border, each with two spine groups; telson 

 broadly V-cleft 17 



17. Antenna 1, peduncular segment 3 longer than first three flagellar segments; 



peraeopod 3, segment 6 shorter than width of segment 5; uropod 3, outer 

 ramus distinctly 2-segmented. 



Pseudohaustorius caroliniensis, new species (p. 191) 

 Antenna 1, peduncular segment 3 shorter than first two flagellar segments; 

 peraeopod 3, segment 6 longer than width of segment 5; uropod 3, outer 

 ramus appearing 1-segmented. 



Pseudohaustorius americanus (Pearse) 



18. Pleon side plate 3 rounded behind; uropod 1, rami subequal; urosome 2, 



dorsal margin short, nearly occluded; rostrum and anterolateral angles 

 acute Haustorius Miiller. 19 



