678 
Journal of Agricultural Research 
Vol. XXX, No. 7 
Diameter of head 19 a*; diameter of 
body at nerve ring 45 ju, at base of 
esophagus 60 y.. Esophagus 620 ju in 
length; nerve ring 207 n behind the 
anterior extremity. Excretory pore 
and cervical papillae at same level, 
265 m behind anterior end. Bursa simi¬ 
lar in shape to that of 0. trifurcata 
Rans., 178 At long in lateral view, pre- 
bursal papillae short and inconspicuous, 
16 At in front of the origin of the ventral 
rays. Dorsal ray slender, 32 n long 
from origin to bifurcation, each arm 36 
At long with a very short external branch 
near the tip. Externo-dorsal ray ends 
near the margin of the bursal membrane 
close to the limit of the thick dorsal 
level, each spicule gives forth two thin, 
nearly transparent, acute processes, di¬ 
rected posteriorly, each process about 
29 At long. Gubernaculum absent. 
Female: Length 6.75 mm., maximum 
thickness 89 At, in vicinity of the vulva. 
Head 22 At in diameter, esophagus 670 ix 
long; nerve ring 215 At behind anterior 
end. Excretory pore and cervical 
papillae at same level, 280 n behind 
anterior end. Vulva a transverse 
crescentic slit, nude, 1.17 mm. in front 
of posterior extremity. Anus 144 a* in 
front of tip of tail. Tail gradually 
attenuated, rounded at tip. Combined 
length of oviejectors about 450 jjl; 
sphincters 45 At long by 64 At in diameter. 
/OOm 
Fig. 1 .—Dictyocaulus hadweni, n. sp. A, bursa of male; B, spicules and gubernaculum 
lobe. Dorsal lobe 80 a* long, 48 a* wide 
and 45 a* thick, granular, not transpar¬ 
ent as the bursal membrane. Tip of 
medio-lateral ray only half as far from 
that of postero-lateral as from that of 
externo-lateral. Latero-ventral ray 
bent so as to bring its tip in close prox¬ 
imity with that of the ventro-ventral. 
Spicules from 130 to 140 u long, simi¬ 
lar in length but differing in conforma¬ 
tion. The right spicule ends in a short 
corkscrewlike hook, while the tip of the 
left is acute and slightly curved. On 
the ventral aspect of each, at about 42 
a i before the posterior extremity there 
is a small boss, directed toward the 
median line of the worm. At the same 
Eggs ovate, 64 to 77 jx long by 45 to 
48 n wide. 
Habitat: In fourth stomach and 
duodenum of Bison bison. 
Locality: Canada; Wainright, Al¬ 
berta, January 28, 1923; S. Hadwen, 
collector. 
Type: United States National Mu¬ 
seum, Helminthological Collections, 
No. 26101; paratypes Nos. 25960, 
26103. 
This species is most closely related to 
0. trifurcata Rans., and in his key 
(Ransom) 3 it would run out at that 
species. The spicules are, however, a 
trifle smaller in the present species, and 
are of a different conformation. 
3 Ransom, B. H. the nematodes parasitic in the alimentary tract of cattle, sheep, and other 
ruminants. U. S. Dept. Agr., Bur. Anim. Indus. Bui. 127, 132 p., illus. 1911. 
