NO. 2131-. 



NEMATODE PARASITE.^! OF RODENTS— HALL. 



161 



Type-sj)ecies. — Tlcligmosomoidcs linstowi Hall, 1916. 

 I am not sure that my interpretation of von Linstow's figures of 

 the bursa is correct. The figures present some peculiarities. 



HELIGMOSOMOIDES LINSTOWI Hall, 1916, new name. 



Synonym. — Strongylus ■polygyrus Dujardin, 1815, of von Lin- 

 stow, 18785 and 1879«. 



Specif c diagnosis. — Ileligmosomoides (p. IGO) : Worm, reddish, 

 spirally coiled. Mouth aperture triangular with four circumoral 

 papillae. Cuticle dilated about head and with 10 longitudinal stria- 

 tions, in part wavy, along 

 body. Transverse stria- 

 tions present and spaced at 

 about the same interval as 

 the longitudinal. 



Male 4 mm. long and 78 /x 

 thick. The bursa structure 

 is that given in the generic 

 diagnosis. The spicules are 

 540 p. long. 



Female 7.2 mm. long and 

 96 II thick. The anus is 98 

 ju, from the tip of the tail, 

 the tail ending in a fine 

 terminal point 16 ju, long. 

 The vulva is anterior, 240 

 /x from the anterior end. 

 The vagina is 720 ju, long 

 and is directed posteriorly 

 (presumably). It joins an 

 ovijector 180 /;. long (fig. 

 207). At the anterior end 

 of this is a spherical body. 

 Anterior of the latter is a muscular uterus 180 /x long and anterior 

 of this is the ovary. The eggs are 75 by 43 fi in diameter. 



Life history.— In eggs placed in moist earth embryos (fig. 208) 

 develop in eight days. The embryo is 310 /x long and 23 /x thick. 

 The mouth has two conical projections and the tail is awl-shaped. 

 The esophagus is 1/2.4 and the tail 1/4.7 of the total body length. 



Host. — Mic7'otus arvalis {Arvicola campestris). 



Location. — Intestine, partly in saclike depressions apparently 

 caused by the worm. 



L.ocality. — Germany. 



10600°— Proc.N.M.vol.50— 16 11 



Fig. 207.— Heugmosomoides 

 LINSTOWI. Vagina and 

 OVIJECTOR. Enlarged. 

 After von Linstow, 1882. 



Fig. 20S. — Heligmoso- 

 moide.s linstowi. 

 Embryo. Enlarged. 

 After von Linstow, 

 1882. 



