196 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



Remarks.— The genus Pseudohaustorius is represented mainly 

 along the coasts of the southeastern United States and the Gulf of 

 Mexico (Bousfield, in prep.). P. borealis is probably the most north- 

 erly of the component species; hence, the specific name. It differs 

 from P. americanus and P. caroliniensis mainly in the more elongate 

 and spinose peraeopod 4, the smaller coxa of peraeopod 5, and the un- 

 cleft telson. It is also a deeper-water, more offshore species, not 

 uncommon in the Georges Bank region to lat. 42 °N. 



Genus Haustorius Miiller 1775 



(emendation of Stebbing, 1906, Barnard, 1957) 



Medium to large haustoriids. Head broadest medially, lateral 

 margins strongly convex, rostrum strong, sharply acute, antennal 

 sinus deep; body broad, strongly arched, lateral lobes of peraeon 

 well developed; pleosome relatively short, abruptly narrowing beyond 

 peraeon 7; hindmargm of segment 3 strongly decurved or reflexed; 

 side plate (especially 3) margins rounded. Urosome markedly re- 

 duced, overhung by pleosome; urosome 1 short, posteroventral 

 lappet well developed; urosome 2 very short. 



Antenna 1: peduncular segment 2 margins thickly plumose; flagel- 

 lum calceolate in both sexes, accessory flagellum 4-segmented. 

 Antenna 2: peduncular segment 5 broad, not lobate behind; flagellum 

 long, noncalceolate in male. Upper lip broad, apically pilose. Lower 

 lip: inner lobes large, subtruncate distally. Mandibular incisor 

 strong, few cuspate, lacina present on one side; accessory blades 

 numerous (9-12); palp long, comb spines numerous. Maxilla: inner 

 plate large, margin richly setose; palp slender; accessory baler lobe 

 very large and long ciliate. Maxilla 2 : outer plate extremely large, 

 lunate, richly plumose; inner lobe long, narrow. Maxilliped plates 

 narrow; palp with slender, sharply geniculate terminal segment. 



Gnathopods slender, coxae semilunate. Gnathopod 1 : dactyl sim- 

 ple, strong. Peraeopods 1 and 2 normally fossorial; posterior lobe of 

 segment 5 in peraeopod 1 with median and marginal spines. Peraeo- 

 pods 3-5, segments 4-5 broadly expanded. Peraeopods 4 and 5 not 

 greatly longer than peraeopod 3. Peraeopod 4: segment 6 sub- 

 linear, not spatulate. Peraeopod 5: posterior border of segment 5 

 very short. Coxal gills slender, subequal. Brood plates slender, 

 sparingly setose, vestigial on peraeopod 3. 



Pleopods very strong, outer ramus 18-22-segmented, inner 15-seg- 

 mented. Uropods bu-amous. Uropod 1: inner ramus not shorter 

 than outer, with posterior spines and setae. Uropod 2: peduncle 



