ArticLe VIII.—Acanthocephala from the Illinois River, with Descrip- 
tions of Species and a Synopsis of the Family Neoechinorhynchidae.* 
By H. J. VAN CLEAVE. 
INTRODUCTION 
There has been no published record of extensive study upon the 
Acanthocephala from fresh-water hosts for any part of North America. 
The only regional studies pursued in this country have been those of 
Linton (1889, 1891, 1901, and 1905) on the Acanthocephala of marine 
fishes, from New England southward along the Atlantic Coast. Most of 
the European studies aside from Zschokke’s (1884), and a few others, 
have been compilations of host records from results of investigations in 
widely scattered. regions. Usually these lists have ignored the geograph- 
ical distribution of the parasites or have implied for them a distribution 
equivalent to the distribution of the hosts. Because of inaccuracies in 
many of the early investigations and the numerous erroneous identifica- 
tions of European species these lists have comparatively little biological 
value. 
The present paper is based upon an intensive search for Acantho- 
cephala in the vertebrates of the Illinois River, especially in the region of 
Havana, Illinois. The collections were the result chiefly of work during 
the summer of 1910, though a number of subsequent observations have 
been included in the tabulated results along with a few instances of hosts 
examined at other points on the river, namely at Peoria and at Beards- 
town, Illinois. 
It is especially significant that the first study of this sort should be 
upon forms found in the Illinois River. The life of this stream has 
received so much attention at the hands of Professor Forbes and his asso- 
ciates in the Illinois Natural History Survey that the studies relating to 
its life have frequently been referred to as the first significant and the 
most extensive of those dealing with river life. Hitherto practically no 
attention has been directed to the parasitic fauna of this region. The 
interrelationships existing between internal parasites and their hosts are 
of such fundamental nature that no survey of the life of any region is 
complete if the parasitic fauna is left out of consideration. 
ACKNOWLEDGMENTS 
Generous cooperation on the part of a number of individuals has 
enabled me to present a more complete study of fresh-water represen- 
*Contributions from the Zoological Laboratory of the University of Illinois, 
No. 134. 
