HAUSTORIIDAE OF NEW ENGLAND BOUSFIELD 201 



posterior margin with proximal setae; segment 4 broader than deep, 

 one group of posterior spines and 4-6 groups of facial spines ; segment 

 5 much broader than long, posterior lobe produced distaUy, 3 rows 

 of facial spines; segment 6 linear, with 5 groups of anterior spines 

 and a few long terminal spines. Peraeopod 4: coxal plate shallow; 

 segment 2 not broader than deep; segment 4 with about 5 posterior 

 marginal spines and 3 rows of short facial spines ; segment 5 quadrate, 

 posterior margin nearly straight; segment 6 short and linear with 3 

 posterior spine groups and longer terminal spines. Peraeopod 5: 

 coxal plate with subacute posterior lobe; segment 2 orbicular, pos- 

 terior margin virtually bare; segment 4 short, posterior lobe con- 

 siderably produced, posterior margin short, with 2 spines; segment 

 5 longer than 6, distall}^ broadest, with vhtually no posterior margin, 

 facial groups of setae only; segment 6 basally broad, marginal spines 

 rather long. Brood plates broad, long, those of peraeopods 1 and 2 

 with 30-50 marginal setae, that of gnathopod 2 smaller; plate of 

 peraeopod 3 a small lobe with 6-7 marginal hairs. Coxal gills elongate 

 anteriorly. 



Pleosome side plate 3 produced posteriorly into a long stout spur 

 or spine; about 6 clusters of lateral plumose setae. Side plates 1 

 and 2 posteriorly acimiinate. Pleopods with rather slender rami; mner 

 12-segmented, outer 17-segmented. 



Uropod 1: peduncle slender, longer than rami, posterior margin 

 with a few slender sprues; 3 short inter-ramal spines; rami slender, 

 spinose above, terminal spines long; inner ramus with 4 long, singly 

 inserted, marginal setae and terminal spine cluster. Uropod 2: rami 

 and peduncle subequal, densely setose. Uropod 3: outer ramus 

 slightly longer than inner, 2 segments subequal, distally with numerous 

 long simple setae; peduncle slender. Telson broad, cleft nearly to 

 base, lobes strongly arched medially, margin with slender spines. 



Male, 4.5-7.0 mm.: Very similar to female, slightly smaller. An- 

 tenna 2 noncalceolate. Slender penes arise ventrally on peraeon 7 

 near base of coxae, and are directed medially. 



Remarks. — This is one of the most common species of semipro- 

 tected sand beaches in the Cape Cod region. Like Protohaustorius 

 deichmannae, it is common northward to Casco Bay, Maine, but is 

 not known from Canada. The species probably extends much further 

 southward than the present New England records indicate. It occurs 

 from the lower intertidal zone to depths of 27 fathoms and m salinities 

 from estuarine to fully marine. The species is named in honor of 

 Dr. Eric L. Mills, who collected the material from which this and 

 other new haustoriid species initially were recognized. 



