Apr 1, 1925 
New Nematodes from North American Mammals 
681 
ber of divisions varying from 5 to 7. 
Internal corona composed of 48 peglike 
elements, each peg about 8 ji long, 
cylindrical, rounded at apex. Internal 
corona situated within the collar, about 
30 n behind the anterior margin. 
Esophagus 1.2 mm. long, clavate, 
greatest diameter 250 ju near the intes¬ 
tinal valve, diameter at buccal capsule 
195 diameter at nerve ring 165 jj. 
Nerve ring surrounding esophagus at 
its anterior fourth. Cervical papillae 
small, situated just anterior to the mid¬ 
dle of the esophagus, excretory pore just 
behind cervical papillae. Bursa trans¬ 
versely oval, dorsal lobe trapezoidal, 
dorsal trunk bifurcated, at about half 
its length, each fork bifurcated near tip. 
On each side of main trunk there is an 
exceedingly short and slender branch. 
Externo-dorsal ray moderately thick, 
parallel, originating halfway between 
the main trunks of the dorsal and lateral 
rays, ending some distance from the 
margin of the bursa. Lateral rays 
stout, postero-lateral and medio-lateral; 
not close together but subparallel; tips 
at margin of bursa, end of externo- 
lateral remote from the bursal margin; 
ventral rays similar in size to the 
laterals, close together, parallel, ending 
on bursal margin. Spicules 1.4 to 1.5 
mm. long, slender, somewhat twisted. 
Gubernaculum wanting (fig. 4). 
Female: 12 mm. in length, greatest 
diameter 645 jj at about middle of 
length. Mouth collar slightly lower 
that that of male but of the same 
diameter. Dorso-ventral diameter of 
buccal capsule 240 jj, equal to the 
greatest depth. External and internal 
coronae similar to those of male. 
Esophagus 1.10 mm. long, 300 jj in 
diameter just before the intestinal 
valve, nerve ring at anterior fourth of 
esophagus, excretory pore at the level 
of the nerve ring, cervical papillae 255 jj 
behind the excretory pore. Tail coni¬ 
cal, slender; anus 315 jj in front of 
extreme tip, vulva 375 jj in front of 
anus. Eggs 83 to 92 jj long by 51 to 
54 jx wide, up to the eight-celled stage 
in uterus. 
Habitat: In colon of Castor cana¬ 
densis , National Zoological Park, Wash¬ 
ington, D. C.; January 22, 1924; E. A. 
Chapin, collector. 
Type: United States National Mu¬ 
seum Helminthological Collections, No. 
25967; paratypes No. 26104. Paratypes 
also deposited in the British Museum 
(Natural History). 
