680 
Journal of Agricultural Research 
Vol. XXX, No. 7 
Castorstrongylus castoris, n. sp. median papillae prominent, lateral 
Synonyms: Sclerostoma sp. Morgan, 1868; 5 papillae obsolete, amphids distinct. 
Strongylus sp. Hall, 1916.® Buccal capsule large, walls 25 m thick, 
Male: 11 mm. in length; greatest internal diameter (dorso-ventral) 240 /*, 
diameter 645 /*, at about the middle of depth 195 n, dorsal gutter distinct, 
Fig. 3.— Castorstrongylus castoris, n. sp. A, anterior end of male, ventral view; B, same, lateral view, 
C, posterior end of female 
l 20 ytA- 
Fig. 4.— Castorstrongylus castoris, n. sp. Bursa, male 
the length. Mouth opening anterior, toward base of capsule lying in a 
surrounded by a prominent collar 285 ju thickened ridge. External corona com- 
in diameter by 60 n in height. Cir- posed of 24 elements, each element 
cumoral papillae situated on collar, sub- fimbriated at its anterior border, num- 
« Morgan, L. H. the American beaver and his works. 330 p., illus. Philadelphia. 1868. 
« Hall, M. C. nematode parasites of mammals of the orders rodentia, lagomorpha, and 
hyracoidea. Proc. TJ. S. Nat. Mus. 50: 1-268, illus. 1916. 
