302 BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



ECHINOCORNUS PECTINATUS, new species 



Plate 21 



Occwrrence. — A dozen specimens, including both sexes, were 

 washed out of the sand on Buzzards Bay bathing beach at Woods 

 Hole, July, 1927 (male holotype, U.S.N.M. No. 63437) ; two females 

 were also obtained from the sand on Nobska bathing beach. 



Color. — Body transparent, with a faint bluish tinge; eggs a dark 

 blue, becoming deeper with development ; eye not visible. 



Femmle. — Body widest through the cephalic segment, and quite 

 strongly tapered backward, the epimeral plates showing plainly 

 on the lateral margins and at the posterior corners of the segments. 

 Genital segment shorter and narrower than the fifth segment, not 

 divided; anal segment vaulted dorsally into a high ridge, which 

 terminates posteriorly in the anal plate, fringed with spinules. The 

 dorsal surface of the ridge is also covered with small spinules dis- 

 tally, and there is a row of spines on each lateral margin above the 

 base of the caudal ramus. The ventral surface of the segment de- 

 scribes the arc of a circle in side view, turning upward posteriorly. 

 The caudal rami are attached to the ventrolateral surface at each 

 corner a little in front of the end of the segment. Each ramus is 

 wider than long and covered with small spines on its dorsal surface 

 and lateral margins. The outer terminal seta is one-third as long 

 as the inner and both are sparsely plumose. On the dorsal surface of 

 each ramus at the outer basal corner is a stout seta extending out- 

 ward and upward. 



Rostrum comparatively large and tongue-shaped, extending in 

 front of the antennae and turned downward at its tip. The first 

 antennae are profusely armed with setae and pectinated spines, and 

 the segmentation is hopelessly indistinct, except at the tip. They 

 are usually strongly hinged between the second and third segments, 

 the distal part turned outward, and with the rostrum they form in 

 front of the head a large letter T. The end segment of the endopod 

 of the second antenna is the longest of the three segments, with a 

 fringe of spinules on its inner margin increasing in length distally, 

 the corner one pectinated; around the tip of the segment are five 

 setae, all geniculate. The middle segment of the exopod is much 

 shorter than either of the others and unarmed; the basal segment 

 has an inner pectinated spine, and the end segment has two apical 

 pectinated spines and an inner filiform seta. 



The mandible has a narrow chewing blade, set with rather coarse 

 teeth, and a biramose palp ; the basal segment of the maxilliped car- 

 ries a single large pectinated spine at its distal corner, the second 

 segment is armed with two longitudinal rows of hairs and a long seta 



