COPEPODS OP THE WOODS HOLE REGION 363 



Genus SAPPHIRINA J. V. Thompson, 1829 



Head separated from first segment, with a pair of corneal lenses 

 on the forehead; entire body strongly depressed; metasome much 

 widened, with or without lateral epimeral plates in the female, 

 always with them in the male; fifth segment abruptly narrowed to 

 half the width of the fourth, or less. Urosome 5-segmented, much 

 narrower than metasome in female, little if any narrower in the 

 male ; abdominal segments with epimeral plates in both sexes ; caudal 

 rami broadly laminate, with no elongated setae. First antennae 3- 

 to 6-segmented; second antennae 4-segmented, prehensile; rami of 

 first four pairs of legs 3-segmented; fifth legs uniramose, 1-seg- 

 mented, each with two minute apical setae. 



Remarks. — The males of this genus are remarkable for their won- 

 derful iridescence, the dorsal surface of the body displaying a me- 

 tallic brilliancy, which surpasses that of any other copepod. After 

 careful histological examination Doctor Ambronn concluded that 

 these are not the spectral colors of a grating, but are interference 

 colors produced by a layer of closely set uniaxial, anisotropic prisms 

 just beneath the chitin integument.^' 



KEY TO THE SPECIES 

 FEMALES 



1. Endopod and exopod of fourth legs subequal 2 



Endopod of fourth leg half as long as exopod, or less 7 



2. Each caudal ramus with a broad, bluntly rounded process at its 



inner distal corner, reaching beyond tip of ramus angusta (p. 364) 



Each caudal ramus with a slender process or spine at its inner 

 distal corner, not reaching tip of ramus 3 



3. Metasome broadly ovate, one-half longer than wide, and nearly 



or quite three times as wide as urosome 4 



Metasome elongate ovate, twice as long as wide, and scarcely 

 more than twice as wide as urosome 5 



4. Fourth segment of second antenna twice as long as third, the two 



together the same length as second segment auronitens (p. 365) 



Fourth segment of second antenna one-half longer than third, 



the two together half as long as second segment pyrosomatis (p. 366) 



5. Head about equal in length and width ; third and fourth seg- 



ments of second antenna together three-fourths as long as 



second segment gemma (p. 368) 



Head definitely wider than long 6 



6. Fourth segment of second antenna same length as third, the two 



together half as long as second segment ovatolanceolata (p. 369) 



Fourth segment of second antenna distinctly longer than third, 



the two together four-fifths as long as second segment vorax (p. 370) 



7. Metasome broadly ovate, only one-fourth longer than wide ; third 



segment abruptly narrowed to two-thirds the width of second 



segment scarlata (p. 371) 



Metasome elongate ovate, one-half longer than wide; third seg- 

 ment but little narrower than second nigromaculata (p. 372) 



"Mittheil Zool. Stat. Neapel, vol. 9, p. 365, 1890. 



