COPEPODS OF THE WOODS HOLE REGION 409 



CALIGODES MEGACEPHALUS Wilson 



FiGXJBE] 256 



CaUgodes megacephalus Wilson, Proc. U. S. Nat. Mus., vol 28, p. 609, pi. 16, 1905. 



Occurrence. — A single female from the mouth of a silver gar 

 {Lepisosteus osseus) at Woods Hole. 



Distribution. — Not found outside the present area. 



Color. — Body a uniform dark yellowish brown, the abdomen and 

 ^^^ strings darker than the other parts ; eye brick red. 



Female. — Carapace orbicular, a little longer than wide; lunules 

 small, semilunar, not projecting; fourth segment half the length and 

 a third the width of the carapace; genital segment without its pos- 

 terior processes as long as the carapace and fourth segment com- 

 bined, widest at jDOsterior end, where on the dorsal surface is a horse- 

 shoe-shaped median lobe, the toe pointed backward. Abdomen six 

 times as long as wide; caudal rami minute, inclined inward, their 

 tips touching. First legs with a single terminal claw; fourth legs 

 2-segmented, Avith two spines, one terminal, the other lateral on the 

 end segment. Total length, 6.1 mm. 



Male. — Unknown. 



Remarks. — This genus and species can be identified at once by the 

 general appearance and the proportions of the different parts. 



Genus LEPEOPHTHEIRUS Nordmann, 1832 



Head fused with first three segments and covered with a carapace ; 

 fourth segment free, without dorsal plates; fifth and genital seg- 

 ments fused; abdomen 1- or 2-segmented; caudal rami short and 

 wide. No lunules; maxillae small and bifurcate; maxillary palp and 

 furca both present; first and fourth legs uniramose, second and 

 third legs biramose ; one or two pairs of leg rudiments often present 

 on the fused fifth-genital segment. Egg strings often longer than 

 the body. 



KEY TO THE SPECIES 



FEMALES 



1. Carapace one-half shorter than rest of body ; abdomen 2-seg- 

 mented, basal four times as long as end segment thompsoni (p. 410) 



Carapace distinctly longer than rest of body ; abdomen 1-seg- 

 mented 2 



2. Genital segment as wide as long, fourth legs not reaching its 



center; branches of furca undivided edwardsi (p. 412) 



Genital segment longer than wide, elliptical in outline 3 



3. Fourth legs reaching behind center of genital segment; branches 



of furca vprinkled but not divided nordmannii (p. 411) 



Fourth legs reaching posterior lobes of genital segment ; branches 



of furca divided but not wrinkled hippoglossi (p. 412) 



