C. L. Boulenger 209 
A revised diagnosis of the genus Heligmosomoides is given below, together 
with a new specific diagnosis of H. polygyrus based on the material before me: 
HELIGMOSOMOIDES Hall, 1916. 
Generic diagnosis. Heligmosominae: Body commonly coiled in a spiral, 
with transverse and longitudinal striations. Male with long, filiform spicules. 
Bursa without separate dorsal lobe or middorsal incision. Dorsal ray very 
short with four small branches. The externo-dorsal rays are long and slender, 
with separate origins. The lateral rays arise from a common trunk and are 
divergent. Ventro-ventral and latero-ventral rays divergent with a common 
origin. Prebursal papillae long. Female with a truncated posterior extremity 
bearing a slender caudal spike. Vulva situated posteriorly. 
Type species. H. poly gyrus (Dujardin, 1845). 
Heligmosomoides polygyrus (Dujardin, 1845). 
Synonyms: Strong ylus poly gyrus Dujardin, 1815. 
j, „ von Linstow, 1878. 
Heligmosomum polygyrum Railliet and Henry, 1909. 
Viannaia polygyra Hall, 1916. 
Heligmosomoides linstowi Hall, 1916. 
Small worms, reddish in colour when alive, and usually coiled in a spiral. 
The head, 0*04-0*05 mm. wide, is provided with a cuticular expansion, 
usually asymetrically developed and with conspicuous transverse striations 
(text-fig. 2). Head papillae appear to be present, but their number and arrange¬ 
ment could not be definitely ascertained. 
The cuticle of the body is striated both longitudinally and transversely, 
there are, moreover, 18-20 longitudinal crests. The transverse striations are 
very fine and most apparent along these crests and in the neighbourhood of 
the vulva of the female. 
The oesophagus is short, 0*48-0*6 mm. in length. There is a small buccal 
cavity with chitinous walls. 
Male: 4*5-5*5 mm. long, with a maximum thickness of 0*07-0*09 mm. in 
the posterior part of the body. 
The bursa has a length of 0*17-0*18 mm. and a breadth of 0*3-0*33 mm. 
The dorsal edge of the bursa is almost straight (text-fig. 3), there is no separate 
dorsal lobe or median dorsal incision separating the lateral lobes. 
The dorsal ray is slender and very short, branching dichotomously into 
four small rays, the total length of dorsal ray and its branches measures 
0*02o-0*035 mm. In the neighbourhood of the dorsal ray the bursa is fre¬ 
quently transversely folded, so as to give the appearance of an accessory 
bursal membrane. The externo-dorsal rays are long and slender, they have 
Parasitology xiv j ^ 
