no. 1404. PARASITIC COPEPODS—CALIGIDJE— WILSON. 607 



siclerably more than half the entire width and quite squarely truncate 

 posteriorly. 



Free segment five-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; fifth legs not visible dorsal ly. 



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 papillae as in the female, but the plumose setae 

 much longer. 



Total length 2.25 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-defined species 

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

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

 hatched. 



(hddmulonis, generic name of the host.) 



CALIGUS MONACANTHI KrOyer. 



Caligus monacanthi Kroyer, 1863, p. 59, pi. in, fig. 2, a-e. — Bassett-Smith, 1899," 

 p. 450. 



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

 of a Monacanthus 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- 

 <jii.s product it*. 



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 the posterior corners, as indicated, the setae of 

 (lie fifth legs would certainly be visible. 



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

 with an abdomen as long as indicated, that region would certainly be 

 segmented as in all other known species. 



In the description Kroyer does not notice any differences in the sec- 

 ond antennae and second maxillae, which are characteristic of all males. 

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

 given for the female of prod/uctus, and we note particularly the absence 

 of ])lunios(> 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 



