NO. 2131. NEMATODE PA£x\iSTTES OF RODENTS— HALL. 151 



Specific diagnosis. — Ileligniosoirhwm (p. 149) : Body red, filiform, 

 curved in an arc, somewhat narrowed anteriorly. Cuticle bears two 

 opposed ridges or prominent lines from which regular folds originate 

 on each side and pass obliquely to the rear, like ribs. Cuticle trans- 

 versely striate. Head obtuse, 66 /i in diameter exclusive of the sur- 

 rounding cuticular expansion, and 100 \x. in diameter inclusive of 

 the surrounding cuticular expansion. Mouth round. Esophagus 

 muscular and club-shaped. 



Male 11 mm, long and 170 [x thick. Ratio of length to width, 65 : 1. 

 Bursa 310 /a long, composed of two large lobes, each supported by 

 four rays ( ? ) , and more or less enrolled on one another. Two nar- 

 row spicules 930 y, long. 



Female 16.8 mm. long and 250 /a thick in the middle and 207 /* 

 thick in the rear. Tail narrowing, conical, acute, not mucronate. 

 Anus 100 /* from the tip of the tail. Vulva 630 )u. from the tip of the 

 tail. Utenis provided with muscular ovijector. Eggs 100 to 110 /* 

 long. 



Host. — Microtus arvalls [Arvicola arvalis). 



Location. — Intestine and in tubercles in the stomach. 



Locality. — France ( Rennes ) . 



The above very inadequate description is from Dujardin (1845), 

 and although this is the type-species of the genus, no better de- 

 scriptions and no figures whatever appear to be in existence. This 

 is an example of the difficulties resulting from the proposal of 

 genera by the designation of a type-species without the statement of 

 the generic characteristics. As already noted, both things should be 

 expected of present-da}^ workers. 



HELIGMOSOMUM MINUTUM (Dujardin, 1845) Railliet and Henry, igogrt. 



S7jnony7ns. — Stro7igyli(s minutus Dujardin, 1815; Metastrongylus 

 T/hinutus Molin, 1861«. 



Bpeci-fic diagnosis. — Heligmosomum (p. 149) : Body filiform, red- 

 dish, recurved in an arc. Two membranous alae, 10 fi wide and 

 striated transversely. These striations are less distinct on the cuticle 

 where they occur at intervals of 14.5 ju. The head is alate, abruptly 

 narrowed and obtuse. It is 23 [x thick exclusive of the alae, and is 35 \^ 

 thick inclusive of the alae. The cervical alae are separated from 

 the body alae by an incision at one point. 



Male 2.25 mm. long and 51 to 70 /x thick inclusive of the alae. The 

 ratio of length to thiclaiess is 32 : 1. The bursa is 90 [j. long and 157 jjl 

 wide and is widely opened. It is formed of a double rounded lobe 

 supported by two simple rays posteriorly and by two rays with 

 five digitations laterally. The two filiform spicules are 265 /x long. 



Femrde 2.4 mm. long and a little thicker than the male. Ratio of 

 length to thickness is 34 : 1. The tail is narrow, conoid, and obtuse. 



