A-RT.5. NORTH AMERICAN PARASITIC COPEPODS WILSON. 25 



the first maxillae, which are slender, conical, about three-fourths as 

 long as the mouth tube, each tipped with two long setae. The palp is 

 short, conical, and tipped with two spines of unequal length. 



The second maxillae are peculiar; the two basal joints are much 

 swollen and rather short; the third joint is abruptly narrowed to half 

 the width of the second, but is much longer. It is enlarged and almost 

 squarely truncated at the distal end, produced into a conical process 

 on the outer margin, and surrounded with a fringe of short spines. 

 The fourth joint is hemispherical and is attached to the inner margin 

 of the tip of the third joint. The flat side is turned outward and is 

 surrounded with a fringe of short spines. 



The maxillipeds are large, very stout, and furnished with a power- 

 ful terminal claw. There are three pairs of swimming legs, each 

 transformed into a broad and thin lamella, covered with numerous 

 minute transparent dots. Each leg of the two anterior pairs is 

 notched on the inner margin, but does not show any rami ; the margin 

 of the third legs is entire. 



Color. — Carapace dark brown at the center, paler and yellowish 

 toward the edges; dorsal elytra and foliaceous legs gray- white, cov- 

 ered with minute transparent spots ; free thorax, genital segment, and 

 abdomen dark yellowish brown. 



Total length, 10-15 mm.; carapace, 9.50 mm. long, 7 mm. wide; 

 combined diameter of foliaceous legs, 10-11 mm. ; egg strings, 40-50 

 mm. long. 



Specific characters of male. — While the male resembles the female 

 in size and general appearance, it also differs in several important 

 particulars. The carapace is relatively longer and narrower and is 

 similarly notched at the center of the posterior margin. The antennal 

 area is only half as long as wide. There are no dorsal elytra on the 

 fourth segment, so that the entire body behind the carapace is visible 

 in dorsal view, but is covered ventrally as in the female by the folia- 

 ceous legs. 



Each leg of the first two pairs is notched on the inner margin and 

 carries in the notch a pair of distinct, though rudimentary, one- 

 jointed rami. The appendages are practically the same as those of the 

 female, the second antennae and maxillipeds being a little larger. 



Color the same as that of the female, but appearing darker because 

 of the absence of the dorsal elytra. 



Total length, 8-10 mm. Carapace, 6 mm. long, 4.15 mm. wide. 

 Combined diameter of foliaceous legs, 4 mm. 



Remarks. — This shark parasite is very widely distributed and has 

 been found upon several other kinds of sharks besides those here 

 mentioned. It never occurs in any numbers on a host, but is more 

 often solitary, although occasionally the two sexes are associated upon 

 the same fish. Its favorite location is in the throat of the shark, 



