Wilson New Species of Parasitic Copepods. 129 



erance which represents the rudiments of a plate. The genital segment 

 is small and spindle-shaped without a trace of the posterior spines found 

 in the female. The fifth legs are plainly visible on the ventral surface of 

 this segment. The abdomen is very narrow and made up of two spindle- 

 shaped segments of about the same size ; the anal papillae are like those 

 in the female. The second antennae are much larger and stronger than 

 in the opposite sex, the terminal claws are branched like a stag's horn and 

 are evidently used for clasping organs. The other appendages are like 

 those of the female with the exception of the second swimming legs which 

 have a long conical sexual appendage in place of the large claws of the female. 



Total length of female, 10 mm.; width of carapace, 4.9 mm. Total length 

 of male, 6 mm.; width of carapace, 3.2 mm. The entire animal is a clear* 

 horn color like the finger nails, so transparent as to be invisible on the 

 fish's body. 



This species is very common on the outside surface of the smooth dog 

 fish, almost every fish yielding one or more specimens. 



(gracilis, graceful, slender.) 



Alebion glabrum sp. nov. 



Type from Woods Holl, Massachusetts. No. 8123 U. S. National Museum. 



Female, Carapace orbicular, squarely truncated posteriorly. Frontal 

 plates well defined. Posterior sinuses broad and deeper than in gracilis, 

 the lateral lobes relathely wider and rounded instead of truncate poster 

 iorly. Free segment narrow and carrying a pair of dorsal plates which are 

 nearly circular in outline, in strong contrast to those of gracilis. Genital 

 segment half the width of the carapace, oblong in shape, with nearly par 

 allel sides and smooth rounded angles. The entire surface and the margins 

 of this segment are smooth without a trace of the fringe of spines to be 

 found in other species. The abdomen is two-jointed, the joints about the 

 same size. On either side of the first joint a semicircular wing or thin fold 

 of integument projects laterally from the dorsal surface, the combined 

 width of joint and wings being half that of the genital segment. Terminal 

 segment slightly spindle-shaped and tipped with small anal papillae. 



The egg-strings are wider and longer than those in gracilis, being once 

 and a half the length of the body. The appendages present many differ 

 ences in detail which are of minor value, the chief distinction of the species 

 lying in the relative size and shape of the body regions. 



Male. Carapace distinctly longer than wide and obovate, with the widest 

 portion very far back. Posterior sinuses triangular and flaring widely. 

 Free segment long and narrow, less than half the width of the genital seg 

 ment, and without a trace of the dorsal plates. Genital segment narrow 

 and spindle-shaped, squarely truncated posteriorly with a small spine at 

 each posterior corner. The fifth legs are plainly visible on the lateral 

 margins of this segment near its center. Abdomen made up of two nearly 

 equal segments without the wings which appear in the female. Anal 

 laminae very much larger than in the female and armed with long and 

 slender setae. 



