233 
Lepomis pallidus, Eupomotis gibbosus, Micropterus salmoides, and Perca 
flavescens. 
For N. cylindratus two new host species are reported: Carpiodes 
carpio and Micropterus dolomieu. 
COMPARISON WITH OTHER REGIONAL STUDIES 
In his report on “Fish Entozoa from Yellowstone National Park” 
Linton (1893 : 555) listed but two species of Acanthocephala. They were 
given names of European species. though recent investigation has shown 
that extremely few species of fresh-water Acanthocephala are common to 
Europe and North America. Drawings and descriptions show that one 
species is of the genus Echinorhynchus and that the other is one of the 
Neoechinorhynchidae, though data are insufficient for the determination of 
species. This report by Linton constitutes as thorough a study of Acantho- 
cephala as has been made for any fresh-water habitat in North America 
up to the present time; there is, consequently little data with which to 
compare the results of the present study; and, as indicated on an earlier 
page, there are few valuable European contributions with which com- 
parison may be made. 
Zschokke (1884) made an intensive study of the parasites from 
twelve of the most common species of fresh-water fishes from Lake 
Geneva, in Switzerland. In all, he examined over four hundred indi- 
viduals, which yielded but three species of Acanthocephala; namely. 
Acanthocephalus lucit (= Echinorhynchus angustatus), Pomphorhynchus 
laevis (= E. proteus), and Neoechinorhynchus rutili (= E. clavaeceps). 
Eight of the twelve species of fish studied were parasitized with Acantho- 
cephala. In the locality examined by Zschokke thé number of species of 
Acanthocephala is evidently very low when compared with the number 
of species found in the Illinois River. The genus Acanthocephalus, found 
in the European fishes, is wanting in the Illinois River fauna, while four 
genera of Neoechinorhynchidae occur in the Illinois River fish as against 
a single species revealed by Zschokke’s study. 
Ltthe’s check-list of parasites of European fresh-water hosts (1911) 
includes eight valid species of Acanthocephala characteristic of the fresh- 
water fishes of Europe. One additional species, E. gadi, is found in marine 
and migratory fishes, and is consequently taken into fresh-water habitats 
by the migratory fishes though not strictly characteristic of that habitat. 
Since Ltihe in his list assembled the data concerning all known European 
fresh-water hosts, a comparison of his record with that for the Illinois 
River alone would be wholly inadequate; the writer has consequently 
included in Table II data for all fresh-water species of Acanthocephala 
known to belong to the North American fauna. The writer has previously 
(1915) discussed the difference in numbers of species of Acanthocephala 
infesting Amphibia on the two continents. 
