400 BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



second segment; terminal claw o.f maxillipeds shutting into a socket 

 on basal segment; fifth legs conspicuous dorsally. Total length, 

 13-20 mm. 



Remarks. — This is the largest species of the genus, and is prac- 

 tically always found upon the external surface of its host. Both 

 sexes are also sometimes taken while swimming freely in the 

 plankton. 



CALIGUS BALISTAE Steenstrup and Liitken 



Figure 246 



Caligus halistae Steenstrup and Lutken, Kong. Danske Vid. Selsk. Skrift., ser. 

 5, vol. 5, p. 356, pi. 1, fig. 1, 1861.— Wilson, Proc. U. S. Nat. Mus., vol. 28, 

 p. 601, pi. 15, 1905. 



Occurrence. — Both sexes taken from fins of file fish [Alutera 

 scripta) at Station 2565, Albatross, southeast of Nantucket. 



Distribution. — West Indies (Steentrup and Liitken, Wilson) ; 

 Cape Verde (Brady) ; Sargasso Sea (Brian). 



Color (preserved material). — Body light yellow, tinged in the 

 center of the carapace and genital segment with brown; egg strings 

 orange ; eye reddish. 



Female. — Carapace more than half the entire length; lunules 

 small, circular, and not projecting; fourth segment very narrow and 



rhombic; genital segment wider than 

 long, its posterior margin concave, with 

 lobes but no leg rudiments at the corners ; 

 abdomen short and wide, 1-segmented; 

 caudal rami small and well separated. 



Furca shaped like a bootjack; second 

 segment of maxillipeds with a prominent 

 knob on its outer margin near the proxi- 

 mal end; fourth legs 3-segmented, with 

 ^ -i-r four exceptionally long and stout spines. 



Figure 246.— CaJij/Ms ialistae: a. Total length, 4—4.5 mm. 



Female, dorsal; ft, female, Male.— Car ajmce twice as loug and 



fourth leg • i i /» i 



three times as wide as the rest oi the 

 body; fourth segment even smaller than in the female and 

 rhombic; genital segment semilunar, the lobes at the posterior 

 corners long, acuminate, and tipped with leg rudiments. Abdo- 

 men 1-segmented, as long and half as wide as the genital seg- 

 ment; caudal rami curved inward but not touching. Total length, 

 3.5-4 mm. 



Remarks. — This species is a straggler from the West Indies, which 

 comes into the present area upon some wandering tropical fish. 



