442 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



developed and nearly all carry complete egg strings. This lot is 

 taken as the type of the species and is Cat. No. 32815, U.S.N.M. 



Female. — Carapace orbicular, slightly wider than long, its lateral 

 margins strongly convex, the posterior margin nearly straight. 

 Frontal plates projecting strongly with a deep incision at the center. 

 Grooving of the dorsal surface of the carapace peculiar in that the 

 anterior ends of the lateral grooves are bent abruptly inward toward 

 the midline and do not run forward toward the bases of the first 

 antenna as in most species. A similar arrangement was found in 

 Caligus aliuncus. a But in the present instance there is an additional 

 groove running outward from the anterior end of the lateral groove 

 almost at right angles to the median axis. Where this groove strikes 

 the lateral margin of the carapace it produces a well-defined incision. 



A similar incision was found on the carapace of Caligus schistonyxf 

 but in that species the arrangement of the grooves was radically dif- 

 ferent. The median posterior lobe is considerably more than half 

 the entire width, with a nearly straight posterior margin. The lateral 

 lobes are broad and well rounded, but so short that they do not reach 

 the posterior margin of the median lobe. The fourth segment is about 

 half the width of the genital segment, and is abruptly narrowed just 

 in front of the bases of the fourth legs. The genital segment is 

 barrel-shaped, as long as wide, with nearly straight anterior and 

 posterior margins and strongly convex lateral margins. The pos- 

 terior corners project slightly as blunt lobes, but there are no rudi- 

 mentary legs visible on either dorsal or ventral surfaces. The 

 abdomen has but a single segment, one-fourth the width and one- 

 third the length of the genital segment. The anal laminae are small 

 and each is armed with four very long seta?. The egg cases are nearly 

 twice the diameter of the abdomen and four times its length; the 

 eggs are large and much flattened, about twenty-five in each string. 



The first antenna? are slender, the terminal joint longer than the 

 basal and both well armed with seta?; the second antenna? are small, 

 with a slender terminal claw. The first maxilla? also are small, the 

 basal portion enlarged and nearly circular, the terminal part short, 

 narrow, and strongly curved. The second maxilla 3 are relatively 

 large ; they project well beyond the tip of the mouth tube, and are 

 divided for more than half their length, the two branches being of 

 the same size and length. 



The mouth tube is short and wide with a constriction near the 

 center. The furca is long and slender, its base slightly enlarged and 

 circular in outline, its branches conical, much longer than the base 

 and divergent. The second maxillipeds have a stout basal joint, 

 carrying on its ventral surface near the center a larger flattened 



"I'roc. U. S. Nat. Mus., XXVIII, pi. ix, fig. 103. 

 6 Idem, pi. vi, figs. 65 and 66. 



