198 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



The material of Paulmier (1905) now can be referred with certainty 

 to this species. The known range is from the Gulf of St. Lawrence 

 to Chesapeake Bay. A similar but long rostrate form occurs from 

 North Carolina southwards (Bousfield, in prep.). The species is 

 confined to the intertidal and wave zone sandbars and banks, 

 especially at the mouths of estuaries. The animal burrows in the 

 sand to a depth of 4 inches or more when the tide is out. 



Acanthohaustorius, new genus 



Small to medium large, generally similar to Haustorius (sensu 

 stricto). Head broadest medially, margins convex, rostrum broadly 

 acute. Peraeon lateral lobes prominent. Pleon narrowing abruptly 

 behind peraeon, side plates acuminate, 3rd produced posteriorly into 

 stout spinous process. Urosome somewhat reduced, longer than 

 pleon 3, which overhangs it more or less. Urosome 1 stout, postero- 

 ventral lappet short. Urosome 2 as long as urosome 3, but narrower 

 than uropod 1. 



Antenna 1: flagellum usually calceolate, accessory flagellum 

 2-segmented. Antennae 2: peduncular segment 4 deeply lobate, 

 segment 5 broad, setose; flagellum: basal segment largest. Upper 

 lip broad rectangular, apex smooth. Lower lip: inner lobes broad; 

 outer lobes: inner margin subtruncate. Mandibular incisor mono- 

 or bicuspate, lacinia simple on right side only, accessory plates 

 fairly numerous (5-13) . Maxilla 1 : inner plate setae dis tally plumose ; 

 accessory baler plate moderately large. Maxilla 2 : outer plate broad, 

 not elongate, apex blunt, inner margin plumose distally; inner plate 

 narrow. Maxilliped: plates broad; palp segment 3 stout, geniculate. 



Gnathopod 1: segment 5 usually stout. Gnathopod 2: segment 

 6 slender. Peraeopods 1 and 2 not exceptionally powerful, posterior 

 lobes of segment 5 short, coxa of peraeopod 2 very broad. Peraeopods 

 3-5: segments 4-5 moderately expanded. Peraeopods 4 and 5 not 

 excessively lengthened, peraeopod 3 more than % peraeopod 5. Coxal 

 gills smallest posteriorly. Brood plates rather large, broad, margins 

 richly setose, very small on peraeopod 3. Pleopods strong, outer 

 ramus 13-20-segmented, inner 10-15-segmented. Uropod 1 : peduncle 

 stout, inner ramus shorter, spinose and setose behind. Uropod 2 

 strong, rami and peduncle subequal. Uropod 3: terminal segment 

 of outer ramus long. Telson broad, sharply and deeply notched. 



Type species. — Acanthohaustorius millsi, new species. 



Additional species. — Acanthohaustorius intermedium, new species; 

 A. spinosus (Bousjfield) 1962; A. shoemakeri, new species. 



