NO. 2131. 



NEMATODE PARAmTEti OF RODENTS— HALL. 



69 



shape, the first half of almost uniform diameter, with a gradual 

 taper posteriorly and slightly curved. 



Female 9 to 11 mm. long (von Linstow's measurements of 6.4 mm. 

 must be regarded as those of rather small specimens) and attaining 

 a maximum diameter behind the vulva of 515 to 590 ju,. Head diameter, 

 50 to 70 [JL. The posterior end of the 

 body has a quite distinctive structure. 

 Posterior of the anus is a long tail 

 (fig. 78) vrhich, with the exception of a 

 thin terminal portion, shows in optical 

 section, first the cuticle, externally, then 

 the cellular walls of the prolonged body 

 cavity, and finally the clear area indi- 

 cative of the cavity itself, thus forming 

 five parallel bands. For over half the 

 length of this tail the proximal portion 

 shows only a very fine transverse 

 striation. The remaining distal portion 

 shows a number of definite annular 

 structures, usually 35 to 48 in number, 

 formed by the annu- 

 lar splitting of the 

 cuticle, the part be- 

 tween the separated 

 surfaces of cuticle 

 containing a granu- 

 lar content (fig. 79). 

 The proximal three 

 or four of these an- 

 nuli show an in- 

 creasing size, the first 

 1 being at* times barely 



1 indicated, then there 



are a variable num- 

 ber of uniform size 

 and finally a long 

 series of annuli 

 gradually diminish- 

 ing in size. The 

 granular content gives the gross effect of dark bands and the micro- 

 scopic effect of cuticular areolar markings. At the posterior end of 

 this part of the tail there is a constant nucleus in the median field. 

 The esophagus, exclusive of the esophageal bulb, is 495 to 535 ;Lt long 

 and 68 to 80 \i thick. The esophageal bulb is almost constantly 

 spherical with a fairly uniform diameter in mature females of about 



Fig. 77.— Oxyuris 

 AMBiGUA. Poste- 

 rior EXTREMITY OF 

 male, viewed 

 from the side. 

 Enlarged. After 

 Schneider, 1866. 



Fig. 78.— Oxtdris ambigua. Pos- 

 terior EXTREMITY OF FEMALE. 

 Enlarged. 



