44 



BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



a 



Color. — Body transparent; region around the vulva in the female 

 bright green; the oil drops are an intense rusty red and are devel- 

 oped so numerously, especially in the male, that when there is a 

 large assemblage of the copepods, as in a townet, they give a red 

 color. 



Female. — Anterior body elongate-elliptical in outline, nearly three 

 times as long as wide; urosome half as long as metasome; genital 

 segment enlarged and projecting ventrally; 

 caudal rami longer than anal segment; fifth 

 legs entirely lacking. Total length, 1.2-1.6 mm. 

 Male. — Much smaller than the female; uro- 

 some very narrow, with the anal segment 

 shorter and dilated distally; fifth legs unira- 

 mose, asymmetrical, left leg 5-segmented, the 

 second and third segments somewhat enlarged 

 distally, the fifth segment very small and end- 

 ing in a slender spine; right fifth leg 4-seg- 

 mented, the segments diminishing in width 

 distally, the fourth one virtually an acuminate 

 spine. Total length, 1-1.25 mm. 



Remarks. — After a careful examination of 

 Kr0yer's original type specimens, With has 

 identified Kr0yer's triinutus with Boeck's 

 elongatus., and since the former was described 

 20 years before the latter the species name 

 given by Kr0yer must be retained. This is 

 apparently an arctic species, but extends southward on our Atlantic 

 coast at least to latitude 35° N. 



Family AETIDEIDAE 



Genus AETIDEUS Brady, 1883 



Head in female highly vaulted anteriorly, slightly carinated dor- 

 sally, with a stout bifurcate rostrum; in the male less vaulted, not at 

 all carinated, and entirely devoid of a rostrum. Fused fourth and 

 fifth segments produced at tho. posterior corners into sharp spines, 

 which reach beyond the posterior margin of the genital segment. 

 Urosome 4-segmented in female, the genital segment protruding ven- 

 trally, 5-segmented in male, the genital segment not protruding, the 

 anal segment very short. First antennae reaching the caudal rami in 

 female, just reaching the genital segment in male. Fifth legs lacking 

 in female; right fifth leg lacking in male, left uniramose, 5-seg- 

 mented. One species found here. 



Figure 25. — Pseudocalanus 

 minutus: a. Female, dor- 

 sal ; i, fifth legs, male 



