232 
ADAPTABILITY TO DIFFERENT Host SPECIES 
A number of interesting facts regarding specificity of hosts in fresh- 
water Acanthocephala may be observed in Table I. Tanaorhamphus 
longirostris, Gracilisentis gracilisentis, and Octospinifer macilentus are 
the only species recorded from a single host species. These all belong to 
the Neoechinorhynchidae. Their confinement to a single species is in 
sharp contrast to the adaptability displayed by Echinorhynchus thecatus 
and Pomphorhynchus bulbocolli. However,-as O. macilentus is known to 
occur in a different species of sucker in another locality, the two species 
from the gizzard-shad are the only ones found in the locality under con- 
sideration which present strong evidence of restriction to a single host- 
species. 
Members of the genus Echinorhynchus are among the commonest 
fish parasites, yet in the local fauna under consideration but a single 
species, E. thecatus, represents this genus. The relationship of this 
species to the host is obviously very generalized since it may find lodging 
in the bodies of fishes occupying widely different systematic positions. 
This species occurs not only in the more primitive orders of fish, but 
infests also representatives of practically every order of fish studied. 
It is significant that for the region included in this survey no verte- 
brate host was found bearing larval Acanthocephala. Fish and amphib- 
ians frequently serve either as primary or intermediate hosts for encysted 
larvae which reach maturity in predaceous fish, birds, and mammals. 
Unfortunately, a number of species of snakes were examined before the 
writer began to keep negative records. The examination of snakes in 
other localities within the state, especially in the vicinity of Urbana, has 
without exception failed to reveal any Acanthocephala, either larval or 
adult. 
In an earlier paper the writer (1915) has’ called attention to the 
infrequency of records of amphibian infestation by Acanthocephala in 
North America. Data in Table I are supplemented by his records of 
numerous examinations of both tailed and tailless Amphibia from other 
parts of the state, and none of these records shows acanthocephalan infes- 
tation for the amphibian fauna of the state. 
SPECIES NEWLY CREDITED TO THE ILLINOIS River FAUNA, AND 
New Host-ReEcorps 
The present study has added a number of new records concerning 
the distribution of Acanthocephala, the following four species being 
reported for the first time from Illinois: Echinorhynchus thecatus Linton 
(1891), Neoechinorhynchus cylindratus (Van Cleave, 1913), Pompho- 
rhynchus bulbocolli Linkins, n. sp., and Octospinifer macilentus, n. sp. 
For E. thecatus, twelve additional hosts are added; namely, Lepisos- 
teus platostomus, Hiodon tergisus, Ictiobus bubalus, Carpiodes carpio, 
Cyprinus carpio, Ictalurus punctatus, Pomoxis annularis, P. sparoides, 
