NO. 2131. 



NEMATODE PARASITE,^ OF RODENTS— HALL. 



97 



is midway between the first and tlie cloacal aperture; similar bosses 

 have been noted in Oxym''is stroma^ which Seiirat says is 0. ohvelata. 

 Female 2.9 mm. long Avith a maximum thickness of 275 p.. The 

 body is massive and curved in the shape of a letter S. The tail is 

 one-sixth of the entire body; it attenuates gradually and terminates 

 in a soft point. The esophagus is 400 /x long and the esophageal bulb 

 85 II long. The intestine is wider than the esophageal bulb. The 

 two lateral alae arise posterior of the esophageal bulb, at the level of 

 the vulva, and extend to the region of 

 the rectum, 170 \k anterior of the anus. 

 The vulva (fig. 117) opens on the ven- 

 tral surface, slightly posterior of the 

 esophageal bulb and 100 ^ posterior of 

 the excretory pore ; the vulva is promi- 

 nent for the reason that the vagina is 

 everted, forming a prominent appen- 

 dix GO [i. long. In a young female, 1.8 

 mm. long, and recently fertilized, the 

 vagina is not everted, but the vulva is 

 covered with a maroon-colored plaque 

 which prevents any further attempts at 

 fertilization. The ovijector is directed 

 posteriorly and includes, first, a tubu- 

 lar portion lined with a cuticular mem- 

 brane, corresponding to the vestibule 

 and sphincter, and 120 ^. long, char- 

 acterized by the thickness of its muscu- 

 lar Avail ; second, the musculo-epithelial 

 portion, which has a uniform thickness 

 for 150 [I., then dilates to form an ovoid 

 reservoir, 215 [ji, long, in which the 

 spermatozoa accumulate and where 

 fertilization takes place, and then 

 diminishes to its original thickness 

 and continues posteriorly to the vicin- 

 ity of the rectum, Avhere it divides into two branches which ex- 

 tend anteriorly and parallel to join the uterus. In the young female 

 the uterus is straight and the eggs are arranged in a roAv; in the 

 mature female the uterus occupies all the space about the intestine 

 posterior of the vulva with the exception of that about the rectum. 

 The ovaries are massive, blackish in color, and are situated side by 

 side immediately posterior of the vulva. The eggs are numerous, 

 thick shelled, elongated, and flattened on one face ; they are 84 by 25 

 /M in diameter. 



Fig. 119.— Oxyuris rALL.vRYi. Pos- 

 terior extremity of male, ventr.yl 

 VIEW. Enlarged. After Seurat, 

 1915a. 



lOGOO"— Proc.N.M.vol.50— IG- 



