266 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



6-segmented, with nonplumose setae and without aesthetascs, not 

 geniculate in male. A2 prehensile, with long spines on Bl and B2; 

 terminal spine longer in male than in female. Mx2 2-segmented, 

 ending in strong hook. Mxp 3-segmented. Re of P1-P4 3-segmented; 

 Ri of P1-P3 3-segmented; Ri of P4 1-segmented or absent. P5 

 represented by 2 unequal setae. 



Genus Corycaeus Dana 



Setae of Bl and B2 of female A2 nonplumose; seta of B2 of male 

 A2 finely plumose on 1 margin. Urosome 3-segmented (2-segmented 

 in subgenus Agetus). Ventral process rounded. Re of P1-P3 with 

 1-1-3 outer spines. P4 with rudimentary Ri consisting of small 

 knob bearing 1 or 2 setae; Re with 0-1-1 outer spines. 



Subgenus Ditrichocorycaeus M. Dahl 



Small species characteristic of coastal plankton. Seta of Bl of 

 A2 3 times longer than seta of B2 in female, only slightly longer in 

 male. 



Corycaeus (Ditrichocorycaeus) amazonicus F. Dahl 



FiGUKBS 17a-e 



Corycaeus amazonicus F, Dahl, 1894b, p. 71. — M. Dahl, 1912, pp. 69-71, pi. 10, 

 figs. 1-10.— Farran, 1929, p. 296.— M. S. Wilson, 1949, p. 325.— Grice, 1956, 

 pp. 54-55; 1960, p. 221.— Deevey, 1960, pp. 33-34.— Bjornberg, 1963, p. 83, 

 fig. 44. 



Female. — Length 1.12 mm. Genital segment inflated dorsally. 

 Genital and anal segments subequal; caudal rami slightly longer than 

 genital segment. Re3 of Pi incised at apex so that terminal spine 

 is set at an angle. Re2 and Re3 of P4 subequal; outer seta of Rel 

 extends beyond distal margin of Re2. 



Male. — Length 0.88 mm. Anal segment about % as long as genital 

 segment; caudal rami slightly longer than anal segment. 



Distribution. — East coast of the United States from Block Island 

 Sound, R.I. (Deevey), to Port Aransas, Tex. (M. S. Wilson); Bermuda, 

 Tortugas (M. Dahl); mouth of Amazon River, Brazil (F. Dahl); 

 Rio de Janeiro, Brazil (Farran). In the Puerto Rican collections it 

 appeared in smaU numbers in the bays and over the shelf. 



Corycaeus (Ditrichocorycaeus) subuhttus Herrick 



Figures 17f-h, 18o-c 



Corycaeus subrilatus Herrick, 1887, pp. 48-49, pi. 1, figs. 7A-B. 



Corycaeus lubbocki Giesbrecht. — C. B. Wilson, 1932a, p. 42. 



Corycaeus (Ditrichocorycaeus) americanus M. S. Wilson, 1949, pp. 321-326, pi. 

 18, figs. 1-14.— King, 1950, p. 131 (table).— Grice, 1956, pp. 55-56; 1960, 

 pp. 221-222.— Deevey, 1960, pp. 33-34.— Cronin, Daiber, and Hulbert, 

 1962, p. 72 (table). 



