C. L. Boulenger 
211 
Fig. 4. Heligmosomoides polygyrus. Male bursa, incompletely spread out; the dorsal region is 
folded longitudinally so as to approximate the externo-dorsal rays, the genital cone covers the 
greater part of the dorsal ray. x about 350. 
EXPLANATION OF LETTERING. 
an., anus; bu., buccal cavity; cu., cuticular expansion of head; d.r., dorsal ray; e.d., externo- 
dorsal ray; e.l., externo-lateral ray; g.c., genital cone; int., intestine; l.v., latero-ventral ray; 
mi.,medio-lateral ray; oe., oesophagus; p.l., postero-lateral ray; p.p., prebursal papilla; m., vagina; 
v.v., ventro-ventral ray; vu., vulva. 
