235 
cephala infesting fresh-water hosts of North America exclusive of the 
birds. 
LINKINS’ MANUSCRIPT SPECIES 
In a manuscript thesis filed in the library of the University of 
Illinois, Mr. Ralph H. Linkins described two new species of Acantho- 
cephala belonging to the genus Echinorhynchus. In the course of later 
study he described in manuscript another new species, belonging to the 
genus Pomphorhynchus. One of the species of Echinorhynchus, /. salve- 
lin. Linkins, was subsequently cited and described by Professor H. B. 
Ward (Ward and Whipple, 1918), under whose direction the thesis inves- 
tigation was being conducted. Owing to his entering the Army, Mr. 
Linkins has been unable to put the results of his investigation into form 
for publication, and he has kindly granted the writer permission to quote 
from the manuscript descriptions in order that the species may be def- 
nitely cited in connection with the present work. The specific definitions 
of Echinorhynchus coregoni and Pomphorhynchus bulbocolli are entirely 
the result of work done by Mr. Linkins, to whom the writer wishes to 
give full credit. 
Family ECHINORHYNCHIDAE 
The family Echinorhynchidae was created by Hamann (1892) to 
include all of the Acanthocephala not set off in his other two families, 
Gigantorhynchidae and Neoechinorhynchidae. The species included in 
this heterogeneous group were, until a few years ago, all embraced in the 
one genus Echinorhynchus. Comparatively recent work, dating from the 
studies of Monticelli and of Ltthe, has resulted in the erection of numer- 
ous genera from the disrupted genus Echinorhynchus. All of these 
genera, with the exception of those included in the Centrorhynchidae, are 
still retained in the family Echinorhynchidae. More thorough study of 
this unnatural assemblage of genera will probably lead either to the estab- 
lishing of several families or, at least, to the recognition of subfamily 
groups within it. As the family now stands, little would be gained by an 
attempt to describe it, for there are very few characters common to all of 
the genera. Four genera usually assigned to this family are represented 
in the fresh-water fauna of North America. Each of these genera with 
its included species will be treated separately. 
EcHINORHYNCHUS Zoega, 1776 
D> 
Generic Diagnosis —Acanthocephala of small to medium size, para- 
sitic as adults in the alimentary canal of fish. Subcuticula and lemnisci 
provided with numerous small nuclei or with a few very large finely 
dendritic nuclei. Body proper and neck spineless. Proboscis long, approx- 
imately cylindrical, armed with circles of hooks which are alternate in 
arrangement. Hooks of practically uniform size except those of a few 
basal circles, which are much reduced. Proboscis receptacle coimposed of 
