NEW NEMATODES FROM NORTH AMERICAN MAMMALS 1 
By Edward A. Chapin 
Zoological Division, Bureau of Animal Industry, United States Department of 
Agriculture 
INTRODUCTION 
The nematode worms described in 
this paper were collected from two 
species of mammals, the North Ameri¬ 
can buffalo (Bison bison L.) and the 
North American beaver (Castor Cana¬ 
densis), both of which are of consid¬ 
erable economic importance. The 
bison, once on the verge of extinction, 
is recovering itself to such an extent 
that it has been necessary to thin out 
the herd at Wainright, Alberta, Canada. 
Thanks are extended to S. Hadwen, of 
the University of Saskatchewan, for his 
kindness in submitting the collection 
of worms for study. The beaver, an 
important fur-bearing animal of this 
continent, has received little attention 
from parasitologists. Morgan 2 noted 
the presence of strongyles in the colon 
and cecum but did not give a descrip¬ 
tion. 
DESCRIPTION 
NEMATODES FROM BISON 
Dictyocaulus hadweni n. sp. 
Male: 52 mm. greatest diameter, 
518 p at about the middle, cuticle 
thin and smooth, without transverse 
striations. Head rounded, 89 p in 
diameter, amphids conspicuous, other 
papillae not evident, tube leading from 
amphid reaching the nerve ring. Nerve 
ring about 311 p, excretory pore about 
620 p, behind anterior extremity. 
Esophagus 1.48 mm. long; its width 
at the anterior extremity, excretory 
pore, and just before the intestinal 
valve, 89 p, 104 p, and 178 p, re¬ 
spectively. Caudal bursa moderate in 
size, about 400 p in diameter, nearly 
circular. Dorsal ray divided com¬ 
pletely to base, abruptly trilobed at 
apex, the inner lobe slightly longer and 
thinner than the other two. Externo- 
dorsal ray simple, slender, not quite as 
long as either branch of dorsal ray. 
Postero-lateral and medio-lateral rays 
completely fused, forming a single 
slender ray slightly longer than the 
externo-lateral which is of the same 
thickness. Ventral rays separate to 
base or nearly so, ventro-ventral but 
about half as long as latero-ventral. 
Spicules stout, subacute at apices, each 
with a semicircular transparent wing 
in apical third, from 260 to 300 p in 
length. Gubernaculum oval, feebly 
chitinized, about 85 p long (fig. 1). 
Female: Length about 60 mm., 
greatest diameter about 640 p, at the 
middle of the length. Pharynx about 
100 p deep, very narrow; esophagus 
1.3 mm. long, its greatest diameter 
192 p, just before the intestinal valve. 
Nerve ring 340 p. Excretory pore 
475 p behind the anterior extremity. 
Vulva transverse, lips prominent, sit¬ 
uated at about the posterior third of 
the body length. Uteri divergent, the 
anterior branch reaching nearly to the 
esophagus. Anus 163 p in front of the 
posterior extremity. Tail acute, coni¬ 
cal. Eggs 80 by 35 p, embryonated in 
uteri. 
Habitat: In lungs of Bison bison. 
Locality: Canada, Wainright, Al¬ 
berta, February, 1923; S. Hadwen, 
collector. 
Type: United States National Mu¬ 
seum, Helminthological Collections, No. 
26100; paratypes Nos. 25954 and 25956. 
Compared with D. filaria (Rud.), the 
above species differs in the more abrupt 
termination of the branches of the dor¬ 
sal ray, in the complete fusion of the 
postero-lateral and medio-lateral rays 
and in the longer spicules. 
Besides the type material, there are 
two lots of worms in the helmintho¬ 
logical collections of the United States 
National Museum from Alee americanus 
(No. 18832) and Cervus canadensis (No. 
19456), respectively. While there are 
some slight differences between these 
and the specimens from the type host, 
they can hardly be considered as spe¬ 
cific and they appear to be of the same 
species. 
Ostertagia bisonis, n. sp 
Male: Length 6.2 mm., greatest 
width 80 p, just in front of the bursa. 
1 Received for publication June 30, 1924; issued June, 1925. 
2 Morgan, L. H. the American beaver and his'works. 330 p., illus. Philadelphia. 1868. 
Journal of Agricultural Research, 
Washington, D. C. 
( 677 ) 
Vol. XXX, No. 7 
Apr. 1, 1925 
Key No. A-94 
