386 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiu 



Male. — Carapace proportionally much enlarged and very evenly 

 rounded, the width one and three-quarters times the length on the 

 mid-line. All the thorax joints except the first free as in the female, 

 and diminishing in size backward. 



Dorsal plates on the fourth joint nuich smaller than in the female, 

 scarcely overlapping the base of the genital segment, and bordered 

 with fine hairs. Genital segment oblong, suddenly and considerably 

 enlarged just back of the center, and then contracted abruptly to the 

 base of the abdomen, with a deeply concave posterior margin. At 

 its widest point it is only one-third the width of the carapace, and is 

 about one-fourth longer than wide. Abdomen two-jointed, the ter- 

 minal joint a little larger than the basal and wedge-shaped, the large 

 anal laminse being attached to the inclined posterior margins. Each 

 of them is fully as large as the joint itself, and carries three large 

 and one small plumose setse. 



The appendages are exactly like those in the female, with the excep- 

 tion of the fourth legs; here the rami have not been transformed into 

 laminae, but are each two-jointed and armed with short plumose setae 

 and spines, like the other legs. 



Total length, 8.3 mm.; length of carapace on mid-line, 3 mm.; 

 width of same, 5.2 mm.; length of gential segment, 2 mm.; width of 

 same, 1.65 mm.; length of abdomen, 1.7 mm. 



Color as in the female. 



This species appears fairly common upon the large sharks along 

 our Atlantic coast, and the U. S. National Museum collection includes 

 five lots, all from the mackerel shark, Lamna cornubica. Cat. No. 

 32782 U.S.N.M., six females from a station 120 miles off Woods 

 Hole; Cat. No. 32784, U.S.N.M., three males taken with the females 

 of the preceding lot; Cat. No. 12676, U.S.N.M., six females, locality 

 unknown; Cat. No. 12677, U. S. N. M., six females from Cox's Ledge, 

 Massachusetts; Cat. No. 8107, U. S. N. M., a single female taken on 

 the coast of England. 



DINEMATURA MUSTELI-L^VIS Hesse. 



Dinemoura musleli-lsevis Hesse, 1880, p. 5, pi. i, figs. 1 to 16. 



The description of both sexes as given by Hesse, and the figures, 

 make this an anomalous and entirely original form, unlike anything 

 found in the entire group of parasitic copepods. 



It is stated in the text that the female is 15 mm. long and 8 wide; 

 both full-length figures of the female are a little more than three times 

 as long as wide. The text further states that this sex has three free 

 thorax segments in front of the genital segment, the third one bearing 

 a pair of dorsal plates. The first antennae are four-jointed, the second 

 pair six-jointed; the maxillae are also six-jointed and ^nd in along 

 curved claw. The swimming legs are all biramose, but each ramus 



