378 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39. 



rounded process covered with short spines. In Ufe the two terminal 

 joints are carried folded back against the basal joint, and each 

 antenna points forward and inward in front of the mouth-parts 

 toward its fellow on the opposite side, the distal ends of the basal 

 joints meeting at the mid-line. From each of these distal ends 

 projects a long curved claw, the two crossing each other like the 

 letter X. The labrum is ovoid, with an evenly rounded outline and 

 a smooth surface; the mandibles are very slender and the terminal 

 blade is smooth; each fu\st maxilla is armed with three divergent 

 setfe, of which the one in the center is much smaller than the others. 

 The second maxillae are as slender as the mandibles, and the spine- 

 like terminal portions are covered with short hairs. 



The maxillipeds are large and stout, and are placed well forward; 

 the terminal claw is bent sharply at the angles, and has a large 

 accessory spine or tooth on its outer margin; it also carries a single 

 large plumose seta on its ventral surface, and there are two others 

 on the inner margin of the second joint. The first four pairs of legs 

 have three-jointed rami, all of wliich and especially those of the 

 fourth pair are comparatively long and slender. The arrangement 

 of the spines and setse is as follows: First exopod, I-O; 0-2; 0-3: 

 endopod, 0-1; 0-1; 0-5: second exopod, I-O; I-l; III-7: endopod, 

 0-1 ; 0-2 ; II-3 : third exopod, I-O; I-l ; 1-6: endopod, 0-1 ; 0-1 ; II-2: 

 fourth exopod, I-O; I-l; III-5: endopod, 0-1; 0-1; 1-2. The 

 fifth legs are two-jointed, the basal joint very short, the terminal 

 one long and spatulate and squarely truncated at its distal end. It 

 carries a seta on its outer margin and three at the end, of wliich the 

 middle one is the longest. There is a pair of rudimentary sixth legs 

 projecting from the genital segment just inside the openings of the 

 oviducts; they are in the form of good-sized papillre, each tipped 

 with three long, cylindrical, nonplumose seta? (fig. 200). 



Color a light yellowish brown, darkening to cinnamon brown in 

 the tliicker and more opaque parts of the body. 



Total length, 1.55 mm. Cephalothorax, 0.5 mm. long, 0.8 mm. 

 wide. Length of free segments, 0.55 mm.; of egg-cases, 1 mm. 



(exilipes, exilis, slender and pes, foot.) 



The National Museum collection contains a single lot of tliis 

 species, consisting of 1 5 females taken from the gills of the sheepshead, 

 Archosargus prohatocej^halus, at Beaufort, N. C, in 1905; it is num- 

 bered 38608, U.S.N.M. 



The parasite is a fairly common one, the above number of speci- 

 mens being obtained from half a dozen sheepsheads. 



It may be distinguished from other species by the long claws at 

 the distal ends of the basal joints of the second antennae, and by 

 the slender rami of the swimming legs, particu.larly those of the 

 first and fourth legs. 



