COPEPODS OF THE WOODS HOLE REGION 



71 



color is most dense anteriorly and gradually fades out in the abdomen. 

 On the ventral surface of the body some distance behind the antennae 

 and among the mouth parts is a spot of bright red. This is of con- 

 siderable size, is nearly circular in outline, and stands out promi- 

 nently. (Rathbun.) 



Female. — Metasome twice as long as wide; fourth and fifth seg- 

 ments completely fused, the posterior corners forming acute lappets 

 reaching behind the center of the genital segment; urosome a little 

 more than one-fourth as long as metasome; fifth legs curved, inner 

 margin of basal segment fringed with spines, of second segment with 

 two or three spines only; end segment narrowed distally, with two 

 unequal terminal spines and a single 

 spine on each lateral margin, all four 

 spines pectinate; distal end of second 

 segment and the entire posterior surface 

 of the terminal segment covered with 

 stiff hairs. Total length, 3-4 mm. 



Mal,e. — Considerably smaller than the 

 female; posterior corners of fifth seg- 

 ment rounded and shorter; urosome 

 more than one-third as long as meta- 

 some ; fifth legs very asymmetrical ; right 

 leg 5 -segmented, but only reaching the 

 end of the second segment of the left leg, 

 the latter 6-segmented and very slender ; 

 terminal segment short, with a single 

 terminal seta and a fringe of hairs on 

 the inner margin. Total length, 2-3 mm. 



Remarks. — In his Copepoda of the 

 Danish /wp'O^Z-Expedition, With made 

 this species a synonym of Vanhoffen's 

 hirtipes, but acknowledged that such a 



decision was difficult without specimens of both forms for compari- 

 son, which he did not have. He said size was not of much value in 

 distinguishing species and discarded the characters found in the 

 structure of the fifth legs. Under such treatment almost any two 

 species of a given genus could be made synonymous. This species has 

 not before been reported from American shores. 



Figure 47. — Xanthocalanus bore- 

 aUs: a, Female, dorsal (after 

 Sars) ; b, female, fifth leg; 

 Cj male, fifth legs (after Sara) 



XANTHOCALANUS PINGUIS Farran 



Figure 48 



Xanthocalanus pinguis Farran, Rep. Fisheries Ireland, 1902-1903, pt. 2, p. 39, 

 pis. 8, 9, 1905. — With, Danish /w^roi^-Expeclition, vol. 3, pt. 4, Copepoda 1, p. 

 236, fig. 77, pi. 7 : figs. 2, a-d, 1915. 



