NO. 2131. NEMATODE PARASITES OF RODENTS— HALL. 159 



Leuckart, 1867; Strongylus laevis Dujardin, 1845, of Stossich, 1899; 

 Strongylus costellatus Dujardin, 1845, of Stossich, 1899; Heligmoso- 

 mum poly gy 7mm (Dujardin, 1845) Kailliet and Henry, 1909«. 



SpecifiG diagnosis. — Viannaia (p. 158) : Body red, filiform, thin- 

 ning anteriorly and tightly rolled into a spiral of 6 to 18 turns, 

 impossible to straighten without breaking. Cuticle finely striated 

 longitudinally and transversely, the transverse striation being the 

 more distinct and spaced at intervals of 20 to 22 ju,. The head is nar- 

 row and obtuse and has a diameter, inclusive of its vesicular swelling, 

 of 45 to 55 II. 



Male 6 to 7.2 mm. long and 90 /* thick. Ratio of length to thick- 

 ness 80 : 1. Body rolled in a spiral of five to six turns. Head 24 /i, in 

 diameter exclusive of vesicular swelling, and 42 jx in diameter in- 

 clusive of swelling. Bursa 300 ii long and 250 /a wide, formed of tw^o 

 large lobes more or less enrolled. Two filiform spicules 580 /x long. 



Female 10 to 13 mm. long and 95 to 105 ii thick near the middle, 

 130 to 140 jjL thick posteriorly in the region of tlie uterus. Ratio of 

 length to thickness 120 : 1. Body rolled in 10 to 18 spiral turns. Head 

 27 to 32 jx in diameter exclusive of vesicular swelling, and 55 /* in 

 diameter inclusive of swelling. Tail 20 fx long, thin, conical, diaphan- 

 ous, truncated, and terminating abruptly in a narrow point. Anus 

 75 fi from the tip of the tail. Vulva 300 fx from the tip of the tail. 

 The single uterus is provided with a muscular ovijector. Eggs 66 by 

 62 /x in diameter. 



Hosts. — Microtus arvalh {Arvlcola arvalls). Apodeinus sylcati- 

 cus (Mvs sylvaticus) . 



Location. — Intestine, at times in pedunculated cysts on the ex- 

 ternal aspect of the intestinal wall. 



Locality. — France. 



Travassos (1914&) states that this species should be transferred to 

 his new genus Viannam and it is here transferred to that genus, 

 principally on the authority of Travassos, who has had material 

 representative of both genera and is in a better position to judge 

 W'here Strongylus polygyriis Dujardin belongs than I am. At the 

 same time the available descriptions of Dujardin's species are not 

 sufficiently detailed to warrant the assertion in this paper that Tra- 

 vassos is right. 



Von Linstow (18785 and 1879«.) has described a parasite, wdiich he 

 determined as Strongylus poly gyrus Dujardin, from Arvlcola 

 campestris, but the worm as described and figured differs so much 

 from Strongylus polygyrus and the other species now assigned to the 

 genera Heligmosomum and Viannaia., and from any other proposed 

 genera known to me, that I have transferred it to the new genus 

 Lleligmosomoides. 



