NO. 2i.';i. 



NEMATODE PARASITES OF RODENTS— HALL. 



205 



The head attains a maximum diameter of about 240 ^. The pharynx 

 is about twice as long as it is thick, attaining a length of 140 fi and 

 a lumen diameter of 70 fi. The esophagus attains a length of 3.27 

 mm. and a maximum thiclaiess of about 235 [>.. The nerve ring 

 is located far anterior on the esophagus, about 430 fi from the an- 

 terior extremity in large specimens. The excretory pore is posterior 

 of the nerve ring and 5G0 fi from the anterior extremity of the body. 

 The simple intestine is straight and of fairly uniform diameter from 

 its anterior origin to its union with the cloaca. The posterior ex- 

 tremity of the body is coiled in a spiral and bears two bursal alae 

 (fig. 2GG). Tlie alae are well developed and rugose, with heavy, 

 wavy, transverse markings. The left one is much longer and wider 

 than the right. There are four pairs of 

 preanal papillae, of which the posterior 

 pair are nearly opposite the cloacal aper- 

 ture, and two pairs of postanal papillae. 

 There is an unpaired papilla on the ante- 

 rior edge of the cloacal aperture. The spi- 

 cules are unequal, the right spicule being 

 longer, thicker, and more uniform in its 

 curvature. It attains a length of about 1.2 

 mm. and a thickness near its middle of 30 [x. 

 The distal extremity terminates in a blunt 

 end beset with very small spiny processes. 

 The left spicule has a more irregular curva- 

 ture, tending to abrupt bends, and has a 

 chitinous lamella. It attains a length of 

 about 1 mm. and a thickness, inclusive of the 

 lamella, of about 30 fj., as in the other spicule, or of 17 n for the body 

 of the spicule exclusive of the lamella. Both spicules have an in- 

 fundibular dilation proximally. In the bursal region, the ventral 

 surface of the body is marked by elongate cuticular elevations formed 

 by longitudinal depressions cutting into the prominent transverse 

 cuticular annulations. The tail ends bluntly. The distance from 

 the cloacal aperture to the tip of the tail is about GOO (i in large 

 specimens. The testis extends forward to a distance equal to about 

 twice the length of the esophagus from the anterior end of the body. 

 Feitmle 15 to 40 mm. long v,'ith a maximum thickness of about 

 1.75 mm. The thick posterior portion of the body terminates in a 

 very blunt rounded end just behind the anus, the most posterior 

 portion being toward the dorsal surface. The maximum head diam- 

 eter is about 2G0 \i.. The esophagus attains a maximum length of 

 about 4.3 mm., which is 1/9.3 of the total body length for the speci- 



FlG. 260.— rROTOSPIKUEA MUEIS. 



Bursa, x 34. After 

 Schneider, 1866. 



