212 
Strongylus poly gyrus 
postero-lateral. The ventral rays arise from a common trunk and are markedly 
divergent; the latero-ventral is very thick, being quite twice as broad as the 
other bursal rays, the tip of the ventro-ventral ray is directed towards the 
anterior border of the bursa. Prebursal papillae are well developed and are 
long and slender. 
The simple, filiform spicules are 0-5-0*58 mm. long, their distal portions 
are united. No gubernaculum could be traced. 
Female: 6-2-10 mm. long. The greatest width of the body is in the posterior 
third, where it measures 0-09-0-12 mm.; the width in the middle of the body 
is 0-06-0-08 mm. 
The anus is 0-067-0-1 mm. from the posterior extremity; the tail is conical, 
truncated posteriorly, and bearing a slender, pointed terminal spike which 
measures 0-012-0-018 mm. in length (text-fig. 1). 
The vulva is a conspicuous opening, situated 0-24-0-35 mm. from the tip 
of the tail. The female organs are single; the ovejector is well developed and 
similar in shape to that described by von Linstow (1882), the combined length 
of the vagina and ovejector (exclusive of anterior nonmuscular portion) is 
0-45-0-55 mm. 
The eggs are 0-62-0-78 mm. long by 0-035-0-045 mm. wide, they are in 
the morula stage when laid. 
The systematic position of S. laevis Dujardin remains to be considered. 
Stossich (1899) has suggested that this is a synonym of S. poly gyrus. According 
to Dujardin the two worms are very closely allied and only to be distinguished 
with difficulty. He specially notes that the caudal extremity of the female is 
similar in the two species, S. laevis also having the extremity truncate and 
bearing a terminal spike. In the absence of any description of the male bursa 
we have only the female characters to help us in assigning a position to this 
worm among the genera of Heligmosominae; these strongly suggest that 
S. laevis should be placed alongside S. poly gyrus in the genus Heligmo- 
somoides. 
Seurat (1915) has published a description of a worm from Dipodillus 
campestris in Algeria which he considers to be S. laevis ; his account shows that 
in this form the bursa is divided into distinct dorsal and lateral lobes, and 
possesses a long dorsal ray, the branches of which extend to the bursal margin; 
the female tail is conical with a pointed termination. If these characters are 
correctly interpreted, I think there can be little doubt that Dujardin’s species 
was not dealt with. 
REFERENCES. 
Dujardin, F. (1845). Histoire naturelle des Helminthes ou Vers Intestinaux. Paris. 
Hall, M. C. (1916). Nematode Parasites of Mammals of the Orders Rodentia, Lagomorpha 
and Hyracoidea. Proc. U.S. Nat. Mus. l. 1-258. 
Linstow, O. von (1878). Neue Beobachtungen an Helminthen. Arch. f. Naturg., Berlin, 
. xliv. 218-244. 
- (1879). Helminthologische Studien. Arch. f. Naturg. xlv. 167-188. 
