126 REPORT OF NEW JERSEY STATE MUSEUM. 



Body shaped much as in Cyclops. Cephalothorax elongated, 

 with five distinct segments, first laiige. xA-nterior antennee short, 

 six-jointed, setaceous. Antennules in female large, long, three 

 or four-jointed, ending in strong- claw. Mouth opening in center 

 of very large head, which not beaked in front, placed some dis- 

 tance behind antennules. Mouth-parts inconspicuous, maxilliped 

 stout, ending in a long claw. Four anterior pairs of feet bira- 

 mose, setiferous and each ramus three- jointed. Outer ramus 

 of fourth foot two-jointed. Fifth pair of feet absent or rudi- 

 mentary. Abdomen three to five-jointed, stylets rather short. 

 Ovisacs two, large. 



The animals of this group are more or less like Cyclops in ap- 

 pearance, and at least during part of their existence parasitic. 

 They are represented by fresh-water as well as marine species, 

 many of them living in the gill-cavities of fishes. 



Ergasilus labracis Kroyer. 

 Plate 33. 



Ergasilus labmcis Kroyer, Naturh. Tidssk., (3) II, 1863, p. 303, PI. 11, fig. 



2-a-e. Baltimore, Maryland (on Roccus lineatus). 

 Leidy, Proc. Acad. Nat. Sci. Phila.. 1888, p. 166. Philadelphia market 



(on Roccus lineatus). 



Wilson, Proc. U. S. Nat. Mus., XXXIX, 191 1, p. 329, PI. 42. Wash- 



ington, D. C. Franklin, Va. Wood's Holl, Mass. 



Ergasilus lahraces S. I. Smith, Rep. U. S. F. Com., I, 1871-72 (1873), p. 573 

 (note). 



Ergasilus lahricis Leidy, 1. c, p. 125. Philadelphia market (on Roccus line- 

 atus). 



Description of female. — Form elongate, slender. First an- 

 tennae rather short, four or five times shorter than anterior, broad, 

 six-articulate, setiferous. Posterior antennre slender, four- 

 articulate. Branches of swimming-feet triarticulate. Caudal ap- 

 pendages equally long, ending in two short segments, each 

 trisetose with inner spine much longest. (Kroyer.) 



Remarks. — Leidy first records this from Philadelphia. He 

 found it attached to the gills of the striped bass {Roccus lineatus). 

 "The little crustacean lives suspended on the outer surfaces of 

 the gills, where it is conspicuous, from the white color of its 



