NO. 2131. 



NEMATODE PARASITES OF RODENTS— HALL. 



117 



externo-dorsal rays fall distinctly short of the margin of the bursa, 

 the tips of the other rays reaching nearly or quite to the margin (fig. 

 145). The ventro- ventral and latero-ventral rays are close together 

 and parallel. The tip of the externo-lateral ray is about equidistant 

 from the tips of the latero-ventral and the externo-dorsal. The medio- 

 lateral and postero-lateral originate in a common stem and diverge 

 slightly from the point of bifurcation. The externo-dorsal rays orig- 

 inate at the root of the dorsal ray and are the thinnest of the rays, the 

 other rays being of rather 

 uniform size. The dorsal 

 ray divides into four 

 branches almost at one 

 level, the two outermost 

 branches passing out from 

 the main trunk and the 

 trunk dividing immedi- 

 ately after to form the 

 two terminal digitations. 

 The four branches are of 

 almost the same thiclaiess, 

 the outer branches being 

 a little the longer. Pre- 

 bursal papillae not seen. 

 The tubular alate spicules 

 (fig. 146) are 830 to 955 /x 

 long. At the anterior end 

 they attain a maximum 

 diameter of 32 fi; pos- 

 terior to this point they 

 are from 10 to 16 /x. thick. 

 The alae (fig. 147) attain 

 a maximum width of 21 \).. 

 is deeply bifurcated. The cloacal aperture is near the end of the 

 genital cone. 



Female 8 to 9.2 mm. long with a maximum thickness of 345 to 

 365 ju, the maximum thickness being attained just back of the head 

 and anterior of the vulva. From the thick portion just anterior of 

 the vulva the body diminishes in diameter posteriorly. A short dis- 

 tance back of the vulva the worm bends dorsally (fig. 148). Back 

 of the anus the decrease in diameter is accented, this portion form- 

 ing a cone. Near the tip of the cone there is a break where the sides 

 of the cone tend for a short distance to approach the parallel and 

 then the body terminates in a conical tip. The esophagus is club- 

 shaped, slightly thinned in the vicinity of the nerve ring and increas- 

 ing considerably in diameter posteriorly. It is 945 /* to 1 mm. long 



Fig. 143.— Ransomus rodentorum. Male. Enlarged. 



The gubernaculum is 43 to 53 [jl long and 



