NO. 2131. 



NEMATODE PARASITES OF RODENTS— HALL. 



139 



Genus GRAPHIDIUM Railliet and Henry, 1909o. 



SynonyTn. — Strongylus Mueller, 1780, of authors. 



Generic diagnosis. — Trichostrongylinae (p. 123) : Cuticle marked 

 with a very prominent and striking longitudinal striation. Mouth 

 large, limited by a chitinous ring. A single dorsal ray, bifurcating 

 near its tip and the bifurcation ending in small f orkings. All rays 

 generally divergent, with no adjacent rays 

 close together and parallel. Externo-dorsal 

 rays long and prominent. Spicules long 

 and narrow, branching distally. Vulva in 

 posterior third or fourth of body, at times 

 covered by a cuticular process, the body 

 diameter diminishing abruptly posterior of 

 the vulva. Parasitic in the digestive tract 

 of rodents, 



Tyjye-s pedes. — Graphidiuyn s tr i g o s u ni 

 (Dujardin, 1815) Eailliet and Henry, 1909^/. 



'i/iomm: 



Fig. ISl.— GRAPHIDIUM .STRIGO- 



suM. Bursa, dorsal view. 

 d, Dorsal ray; ed., externo- 

 dorsal ray; cL, e.xterno- 

 lateral ray'; iv., latero-ven- 



TRAL ray; 77i/., MEDIO-LATERAL 

 ray; pL, roSTERO-LATERAL 

 RAY. 



GRAPHIDIUM STRIGOSUM (Dujardin, 1845) Railliet 

 and Henry, igogf?. 



Synonyms. — Strongylus retortaeformis 

 Zeder, 1800, of Bremser, 1821; Strongylus 

 sti'igosus Dujardin, 1815; Strongylus hlasii 

 von Linstow, 1887. 



Specific diagnosis. — Graphidium (p. 139) : 

 Body blood red and filiform. Two small 

 cervical papillae in the form of posteriorly 

 directed teeth, located at some distance from 

 the anterior end. Cuticle with 40 to 60 conspicuous longitudinal 

 wavy striations and a finer transverse striation. 



Male 8 to 16 mm. long, with a maximum thickness near the base 

 of the bursa of 130 to 175 jx (300 ju, according to Dujardin; 600 fx 

 according to Bremser's figures as noted by Dujardin). Head diame- 

 ter 25 to 35 II. Esophagus 365 to 570 /a long, with a maximum thick- 

 ness near its posterior extremity of 50 to 60 [x. Nerve ring 160 to 

 250 ju, from the anterior extremity. The dorsal ray bifurcates near 

 its tip (fig, 181), each bifurcation ending in two small forks, of 

 which the external and shorter bears one papilla, and the internal 

 and longer bears two papillae. The externo-dorsal ray is very long 

 and prominent. The five rays of the lateral and ventral systems are 

 very uniformly and symmetrically spaced (fig, 182). The filiform 

 spicules are 1.1 to 2.4 mm. long. They present a simple tubular 

 construction of almost uniform diameter except at the posterior 

 extremity where they fray out, the spinelike fringing being directed 

 medially. There is a pair of distinct spinelike prebursal papillae. 



