60 



BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



Genus UNDEUCHAETA Giesbrecht, 1888 



Head fused with the first segment, with or without a crest ; fourth 

 and fifth segments fused with rounded posterior corners; urosome 

 4-segmented in female, 5-segmented in male; genital segment asym- 

 metrical ; exopod of second antennae less than twice the length of the 

 endopod; exopod of first leg 2-segmented in female, 3-segmented in 

 male, rami of the three following pairs of legs 3-segmented; fifth 

 legs lacking in the female ; present and biramose in the male, 



KEY TO THE SPECIES (BOTH SEXES) 



1. Head with a moderately high crest ; genital segment in female 



with a ventral spine on the right side major (p. GO) 



Head without a crest ; genital segment in female with a dorsolat- 

 eral spine on the right side minor (p. 61) 



UNDEUCHAETA MAJOR Giesbrecht 

 FiGUBB 39 



Vtideuchaeta major Giesbrecht, Fauna und Flora des Golfes von Neapel, vol. 

 19, p. 227, pi. 37, 1892. 



Occwrence. — One male and two females from trawl wings, Stations 

 2195, 2219, Albatross; five young males and adult females in vertical 



haul, Station 10313, 

 Gratrifpu^; the former 

 stations south of Nan- 

 tucket. 



Distribution. — North- 

 ern Pacific (Giesbrecht) ; 

 northern Atlantic (With, 

 Far ran) ; southern At- 

 lantic (Cleve) ; Cali- 

 fornia coast (Esterly) ; 

 Malay Archipelago (A. 

 Scott) ; Gulf of Maine 

 (Bigelow). 



Color. — Body colorless 

 and not very transparent, 

 with red pigment scat- 

 tered through the bases 

 of the mouth parts, espe- 

 cially the maxillipeds. 

 In the male the plumose 

 setae of the caudal rami, the second antennae, and the mandibles are 

 brightly colored. In alcohol and formalin the body takes on a uni- 

 form pinkish or reddish hue. 



^e^i^iZe.— Head with a prominent crest and a pointed rostrum; 

 posterior corners of fused fourth and fifth segments angular but 



FiGDRB 39. — Undeuchaeta major: a. Female, dorsal 

 (after Sars) ; b, urosome, lateral ; c, male, fifth legs 

 (6 and o after Giesbrecht) ; d, young male, fifth legs 



