NO. 1404. PARASITIC COPEPODS—CALIOID^:— WILSON. 607 



siderably more than half the entire width and quite squarely truncate 

 posteriorly. 



Free segment live-sevenths as wide as the genital segment, and much 

 swollen at the center through the bases of the fourth legs. 



Genital segment ovate, three-sevenths as long as the carapace, with 

 evenly rounded sides; tifth legs not visible dorsally. 



Abdomen a little shorter than the genital segment, two-jointed, the 

 terminal joint three times as long as the basal; the latter considerably 

 wider than long; anal papillse as in the female, but the plumose setae 

 much longer. 



Total length 2.2.5 mm. Length of carapace 1.25 mm.; width of 

 same 1.2 mm. ; length of genital segment 0.6 mm. ; length of abdomen 

 0.5 mm. 



Three specimens, two females and a male, of this well-detined species 

 were obtained from the gills of Hmmulon elegans Cuvier, in the Danish 

 West Indies. The largest female was full size, with ^gg strings just 

 hatched. 



{hdemulonis^ generic name of the host.) 



CALIGUS MONACANTHI Kroyer. 



Caligus monacanthi Kroyer, 1863, p. 59, pi. iii, fig. 2, a-e. — Bassett-Smith, ISQO," 

 p. 450. 



Kroyer obtained what he states to be a male Caligiis from the skin 

 of a Monacantlnis in the West Indies. There was but the single speci- 

 men on which to found this new species. 



After a careful examination of Kroyer's figures and a study of his 

 description, it seems to the author that he must have mistaken the sex 

 of his specimen, and that what he really had was a young female Cali- 

 gus jyroductus. 



The general make-up of the creature is that of a female and not a 

 male; the genital segment is very large for a male, and if it were really 

 that sex with lobes at tlie posterior corners, as indicated, the seta? of 

 the fifth legs would certain!}^ be visible. 



But Kroyer states that there are no seta?. Again, if it were a male, 

 with an abdomen as long as indicated, that region would certainl}^ be 

 segmented as in all other known species. 



In the description Kroyer does not notice an^^ differences in the sec- 

 ond antenni» and second maxilhe, which are characteristic of all males. 

 On the other hand, his description is identical throughout with that 

 given for the female of productus^ and we note particularly the absence 

 of plumose seta? on the terminal joint of the first swimming legs, the 

 group of seven or eight pectinate projections on the outer border of 

 the basal joint of the endopod of the second legs, the widely separated 

 rami of the third legs, while the fourth legs are three-jointed, with 

 four spines, the inner terminal one much longer than the others. In 



