604 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



they were fairly common and every haul of the fish yielded several 

 specimens. Heller did not find any males and the most persistent 

 search in the present instance throughout the entire summer also 

 failed to yield any of that sex. There must be something peculiar 

 in their habits or in the conditions by which they are surrounded to 

 account for such a widespread disappearance of the males immedi- 

 ately after the breeding season. 



The females, especially the young and such of the adults as are 

 without' their egg strings, are very lively when placed in an aquarium. 

 They swim about rapidly and persistently, and rival the most per- 

 nicious of the Caligus species in crawling up above the surface of the 

 water. They also move about over the skin of their host more 

 rapidly than is usual in a Lepeophtheirus. 



LEPEOPHTHEIRUS LONGISPINOSUS, new species. 

 Plate LII. 



Types.—Cat. No. 32810, U. S. National Museum. 



Female. — Carapace orbicular, about as wide as long and half the 

 entire length. Frontal plates wide and distinct, their anterior mar- 

 gin nearly straight with a shallow incision at the center, in the bottom 

 of which can be seen the remains of the frontal filament. Posterior 

 sinuses wide and U-shaped, inclined somewhat toward each other. 

 Median lobe half the entire width and projecting half its length 

 behind the lateral lobes, with a slightly concave posterior margin. 

 Thoracic area semicircular, but much less than half the entire length, 

 owing chiefly to the shortness of the median lobe. Eyes large and 

 situated far forward. 



Free segment short and less than one-third the width of the genital 

 segment, ^\^th concave sides and scarcely any thickening through the 

 bases of the fourth legs. 



Genital segment orbicular, with very evenly curved, sides, the pos- 

 terior lobes short, wide, and blunt, the posterior margin concave. 



Abdomen the same width as the free segment, one-jointed, and 

 about four-sevenths as long as the genital segment. Anal laminse 

 large and oblong, tipped with three long plumose setse, with two 

 shorter ones on the outer margin. Egg strings wider than the abdo- 

 men and three-quarters the entire length of the body, each with 25 

 or 30 eggs. 



Second antennae with an unusually long and slender terminal claw, 

 sharply bent near the tip; the basal joint is armed with a slender 

 spine two-thirds as long as the terminal claw. 



The first maxillae have a swollen circular base on which are two 

 papillae armed with spines, the rudiments of the endopod. The tips 

 of these maxillae are slender, slightly curved, and nearly as long as 

 the terminal claw of the second antennae, which is exceptional even 

 in a male of this genus. 



