No.noj. PARASITIC COPEPODS—CALIGIDM- WILSON. 589 



but are arranged differently. The fifth legs are so small as to be 

 invisible in dorsal view. 



Total length, 4.0 mm. ; length of carapace, 2.46 mm. ; width of same, 

 2.2 mm.; length of genital segment, 1.25 mm.; length of abdomen, 1 

 mm. ; Qgg strings not present. 



Color of specimen preserved in formalin a pale dusky yellow with a 

 large brown area in the center of the dorsal surface of the genital seg- 

 ment, and the two glands in the thoracic area also brown. 



(latifrohs, lafais, wide, andjftww, forehead.) 



This species resembles rapax very closely in its general appearance, 

 but is clearly distinguished from it by the size and shape of the furca, 

 by the relative width and length of the median carapace lobe and the 

 free thorax segment, and by the details of the first swimming legs, 

 particularly the divided claws. From schistonyx, which has the claws 

 divided, this species is distinguished again by the size and shape of the 

 furca, by the great difference in the relative size of the terminal claw 

 on the second maxillipeds, and by the detail of the exopods of the third 

 and fourth legs. 



From chelifer, which also has the claws divided, it is easily told by 

 the simple fact that its abdomen is unsegmented, while that of a female 

 chelifer is two- jointed. There is also a very essential difference in the 

 structure of the second maxillipeds, in the furca and in the fourth 

 legs. In spite of the fact, therefore, that the collection includes but a 

 single female for which neither the host nor the locality is given, there 

 must be established for it a new species. 



CALIGUS BONITO, new species. 

 Plate XIII, figs. 150-153; figs. 5, 12, 13, 14, 15, 29, 30, 35, 37, 38, 40-45 in text. 



Ft male. — Carapace orbicular, with the sides somewhat flattened, the 

 same length and width; posterior sinuses shallow, slightly curved and 

 enlarged at the base. Thoracic area broad, more than half the entire 

 width, somewhat flattened posteriorly and scarcely projecting beyond 

 the lobes; the latter narrow and curved inward (figs. 150, 151). 



Free thoracic segment short and very narrow; much constricted in 

 front of the fourth legs. Genital segment elliptical, two-thirds as 

 wide and nearly as long as the carapace, projecting posteriorly in the 

 form of a blunt, conical lobe on either side of the abdomen. Abdo- 

 men somewhat spindle-shaped, more than three times as long as wide, 

 and two-jointed; the joints about equal in immature females, and pre- 

 senting a very close resemblance to that of the males, but the basal 

 joint three times as long as the terminal in fully developed individuals 

 and the segmentation very indistinct. 



Anal sinus scarcely perceptible; anal laminae of good size, quad- 

 rangular in outline, each terminated by five plumose setae. 

 Proc. X. M. vol. xxviii— 01 38 



