636 PROCEEDINGS OF THE NATIONAL MUSEUM. 



Specific characters q/" /eTnaZe.— Cephalothorax comparatively \ery 

 small, oval in outline, strongly flattened dorso-ventrally, and covered 

 with a distinct doi-sal carapace. Trunk slender, obclavate, narrowed 

 where it joms the cephalothorax and with the firet one or two thorax 

 segments well difi'erentiated ; broadest and thickest at the posterior 

 end, which is well rounded and terminates in two cylindrical processes, 

 on a level with the ventral surface and somewhat div^ergent; between 

 these processes on the median line is a small genital process; egg 

 strings narrow and as long as the body; eggs large and somewhat 

 flattened anteroposteriorly, arranged in 4 to 6 longitudinal rows, 

 about 150 eggs in each string. Basal joint of firet anteima much 

 enlarged, the other three joints diminishing regularly in size. Exopod 

 of second antennae only one-fourth the diameter of the endopod, 

 distinctly two-jointed, and ending in several short spines. First 

 maxillae tripartite, one ramus terminal, the other two on the inner 

 margm, palp well developed and tipped with two short and curved 

 spines. Second maxillae as long as the trunk, slender, cylindrical, 

 and slightly swollen at the tip, where they are furnished w\th. a small 

 bulla. Maxillipeds situated between the bases of the second maxillae, 

 with a stout basal joint armed on the inner margin with two rounded 

 knobs cov-ered with spines, terminal claw rather slender, with a bunch 

 of accessory spines near its tip. 



Color, a uniform grayish-white, but \arying greatly in specimens 

 from different hosts and also in different specimens from the same host. 

 Van Beneden (1851, p. 120) obtained this species from four dift'crent 

 genera of Plagiostoma, Musteius, Trygon, Goleus, and Scyllium. He 

 notes that some of the parasites had yellow bands on the heads, 

 antennae, second maxillae and maxillipeds, in others these organs 

 were all of a bright red color, while in still othere this same red 

 color was confined to the anterior part of the thorax. Similar colors 

 are found in certain of the Lernaeidae whose attachment organs are 

 buried in the tissues of the host, and both there and in the present 

 species the color is remarkably permanent, withstanding strong 

 alcohol for many years. 



Total length, 10 to 15 mm. Length of cephalothorax, 1.5 mm.; 

 of trunk, 9 mm.; of posterior processes, 2 mm.; of egg strings, 10 

 mm. 



Specific characters o/ waZe.- Cephalothorax ui line w^itli the trunk 

 axis, half the entire length, considerably larger than the rest of the 

 body, and covered with a distinct dorsal carapace. Trunk cylmdrical, 

 sUghtly increased hi diameter at the center and indistinctly segmented ; 

 toward the posterior end on the ventral surface may be seen the two 

 genital openmgs for the extrusion of the spermatophores ; behind these 

 but thoroughly fused with the trunk is a small unsegmented abdomen, 

 which carries a pair of anal laminae attached to its posterior margin 



