600 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



The endopod of the first pair is much shorter than the exopod and 

 is without set*. The rami of the second pair are about equal in size. 

 The third pair have no endopod but only a slight swelling where it 

 will later appear. The fourth pair are simple and very short. 



Total length, 1 mm.; length of carapace, 0.56 mm.; width of 

 carapace, 0.47 mm. 



Groundwork colorless but with the entire dorsal surface thickly 

 sprinkled with rust-colored spots and lines. Tliis fact, together with 

 the shape of the mouth tube, is sufficient to identify the chalimus, 

 since in other species this stage has a very limited amount of pigment. 



This species was found upon the outer surface and in the gill cavity 

 of the sea catfish, Felichthys marinus, the chalimus being found fas- 

 tened to the pectoral fin. The female is lively, swims about actively, 

 and lives a long time in captivity. It is singularly free, for a Caligus, 

 from the pernicious habit of crawling up out of the water and remain- 

 ing Chere till dried. 



The distinguishing characters are the color, the long and narrow 

 mouth tul)e, the weak first and fourth legs, and the wide separation 

 of the rami of the third legs. The toothed spines on the exopod s of 

 the second legs are also peculiar. 



LEPEOPHTHEIRUS MONACANTHUS Heller. 



Plate- LI. 



Lepeophtheinismonacanthxs Heller, 1865, p. 183, pi. xvi, fig. 3 — Bassett-Smith, 

 1896, p. 456. 



Female. — Carapace ovate, considerably more than one-third the 

 entire length and a trifle wider than long. Anterior margin of the 

 frontal plates nearly straight and incised but little at the center. 

 They are also not distinctly separated from the carapace but the two 

 are fused more than in other species. 



Posterior sinuses narrow, shallow, and inclined considerably toward 

 the central axis. Median lobe about half the entire width, not pro- 

 jecting beyond the lateral lobes, and emarginate posteriori}^ Tho- 

 racic area small, two-fifths of the length of the carapace, its outline 

 the arc of an almost perfect circle. 



Digestive glands small, shaped like a beehive, with the rounded 

 ends inclined inward toward each other. Eyes small and placed far 

 forward, with inconspicuous otocysts. 



Free segment as long as wide, half the width of the genital segment 

 with both ends convex and projecting into the carapace and genital 

 segment, respectively. 



Genital segment ovate, six-sevenths as long as the carapace, with 

 evenly curved sides and short rounded lobes at the posterior corners. 

 Fifth legs not visible in dorsal view. Abdomen conical, about the 

 same width at its base as the free segment, but tapering rapidly 



