NOTES ON 
AMERICAN PARASITIC COPEPODA. 
No. I. 
BY R. RAMSAY WRIGHT, M.A., B.Sc. 
Professor in University College, Toronto. 
In the course of some helminthological investigations concerning 
the Fresh-Water Fishes of this region, the results of which I hope 
to publish shortly, my attention has occasionally been attracted to 
Parasitic Copepoda, the careful examination of which I have hitherto 
been obliged to defer. The present paper has for its object the 
consideration of three of these forms. 
I. 
ERGASILUS CENTRARCHIDARUM, 7. sp. 
The gills of various members of the family Centrarchide are 
found in this neighbourhood to be infested by a small species of 
Ergasilus, which usually occurs abundantly on infected individuals. 
I have observed that the same parasite may also occur on the Perch, 
but it is much more commonly met with on the Rock Bass (Amblo- 
plites rupestris), the common Sun-Fish (Hupomotis aureus, Gill and 
Jordan), and the Long-Eared Pond-Fish (Lepomis auritus [L.] Raf.) | 
especially on the first of the three. I have only met with female 
specimens. 
CHARACTERS. 
Length of body, exclusive of furcal bristles, 4 mm., of eyg-sacs I 
mm. Cephalothorax nearly as broad as long. Median constriction 
barely noticeable. The longest of the antennulary bristles as long 
as the antennule. Mandible without palp. Basal joint of natatory 
limbs naked. Ramus internus of Ist pair, with single bristle, on 
inner border of Ist and 2nd joints, and & terminal bristles: of 
succeeding pairs, with 2 bristles on the 2nd joint. Ramus externus 
of Ist pair with 1 spine on outer border of Ist, 2 on outer border of 
3rd, and a bristle on inner border of 2nd joints: of succeeding 
18 
