COPEPODS OP THE WOODS HOLE REGION 301 



inner one borne on a short process and, together with the outer one, 

 filiform, the other two ordinary plumose setae. Total length, 0.4—0.5 

 mm. 



Male. — A little smaller and more fusiform than the female; 

 cephalic segment nearly half the body length ; rostrum swollen at its 

 base. First antennae much enlarged, the fourth segment almost 

 spherical and turned outward at right angles to the basal segments. 

 The genital segment is distinctly divided ; the anal segment is almost 

 twice the length of the penultimate segment, and the caudal rami 

 are not so widely separated as in the female. The swimming legs 

 show no sex modifications, but are like those of the female. The 

 basal expansion of the fifth legs is much reduced and does not reach 

 the center of the distal segment ; it carries two small apical setae and 

 three spines on its inner margin. The distal segment is as wide as 

 long, with a fringe of hair on its outer margin and five apical setae, 

 the outer one longer than the others and filiform. The sixth pair of 

 legs is represented by a single seta on either side of the ventral 

 surface of the genital segment. Total length, 0.35-0.45 mm. 



Remarks. — This species can be recognized by its small size and 

 stout appearance and by the wide separation of the caudal rami in 

 the female, as well as the large size of the ovisac, which reaches be- 

 yond the tips of the apical setae of the caudal rami. It is not so 

 abundant as the preceding species, but resembles it closely in its 

 habits and is fully as active. 



ECHINOCORNUS, new genus 



Body somewhat depressed, metasome much wider than the uro- 

 some ; head fused with the first segment and shorter than the rest of 

 the metasome ; rostrum large and prominent, well defined at its base. 

 Urosome 2-segmented in female, 3-segmented in male; anal seg- 

 ment very highly vaulted dorsally, the anal operculum raised above 

 the rest of the surface ; caudal rami attached to the ventral surface 

 of the anal segment, their apical setae half the body length. First 

 antennae 6-segmented, profusely armed with setae and pectinated 

 spines, strongly hinged in the male. Both rami of second antennae 

 3-segmented, the exopod attached to the side of the second endopod 

 segment. Mandibular palp biramose ; maxilliped with a stout termi- 

 nal claw. Rami of first four pairs of legs 3-segmented, the exopods 

 armed with wide, pectinated spines and fringed on their outer mar- 

 gins with spinules. Segments of fifth legs completely fused into a 

 small lamella, the only part distinguishable being the outer process 

 of the basal segment. A single large ovisac. 



Genotype. — Echinocorwus 'pectinatyas^ new species^ 



