138 REPORT OF NEW JERSEY STATE MUSEUM. 



Argulus versicolor Wilson. 



Plate 38 



Pike Louse. 



Argulus versicolor Wilson, Proc. U. S. Nat. Mus., XXV, 1903, p. 716, PI. 20, 

 PI. 26, fig. 83. Powdermill Pond, Warren; Wickaboag and Podunk 

 Ponds at BrookHeld; Lake Lashaivay between Brookiicld and Spencer; 

 Ashley Ponds at Holyoke ; Congamon Ponds at Southwick, all in Massa- 

 chusetts (on Esox reticulatus) . 



Description. — Carapace orbicular, long as wide. Antero- 

 lateral sinus shallow or very slight. Posterior sinus rather nar- 

 row, its length a little less than one-third length of carapace, and 

 its width about half its own length. Unlike any other species, 

 the larger chitin ring in the carapace lobes extends forward 

 opposite base of posterior maxillipeds, concave on its inner sur- 

 face at the anterior end, so that into this concavity the other 

 much smaller ring fits, and thus the front of the carapace is 

 clear. Sucking-disks of moderate or medium size, placed near 

 front edge of carapace symmetrically distant about equal to 

 diameter of either. Posterior maxillipeds well armed, medium 

 in size, and somewhat wedge-shaped basal plate with long blunt 

 teeth. Large antennae long, furnished with very long sharp 

 spines and powerful hooks, those at base of second antennae with 

 complement of other smaller ones. Proboscis long and wide, 

 and narrow sting very sharp. Body projects but little beyond the 

 carapace, with the thoracic segments small and the posterior not 

 projecting over the abdomen. Latter ovate, its length about two- 

 sevenths entire length of body, a trifle longer than wide. Very 

 narrow anal sinus slit-like, only extending for about last sixth 

 in length of abdomen. Abdominal papillae subterminal. Swim- 

 ming-legs extend far out beyond edge of carapace and thus very 

 long. Lobes of last pair of swimming-legs of moderate size, 

 boot-shaped and just reaching edge of abdomen. Flagella pres- 

 ent and thickest papilte at oviduct opening of g-ood size. In 

 male second legs with large conical projection on their hind sur- 

 faces at outer end of basal joint. A similar and much smaller 

 one in relative position on third legs. These legs also with 



