ON GROUSE DISEASE, ETC. 
167 
Order.—NEMATODA, Rudolphi. 
Family.— Strongylid^e, Dujardin. 
Species.— Strongylus pergracilis, T. S. C. 
(The very slender strongle.) 
Characters. — Body filiform, finely striated, gradually 
diminishing in front, uniform in thickness below; head 
bluntly pointed, with a simple oral aperture ; tail of the male 
furnished with a bilobed bursa, each half supporting four 
pointed rays, spicules two, thick, and slightly divergent; 
tail of the female slightly swollen above the subterminal anal 
orifice, rather sharply pointed at the tip; vaginal opening 
situated at the upper part of the inferior sixth of the body. 
Description of figures.—Strongylus pergracilis : — a, head 
and neck; b, tail of the male, viewed from the front; 
c, another view, showing the expanded bilobed hood, the 
two spicula, oval glandular organs above, and the bursal 
rays ; d, e , lateral and oblique views of the tail of the male ; 
/, tail of female, with anal outlet and fold of the inferior 
uterine tube; g, portion of the body of the female showing 
the reproductive papilla, vaginal passages, and constrictions, 
with lower portions of each uterine tube, also the digestive 
canal; h } three of the ova. 
length of male to f"; body in diameter, tapering 
