NO. 2131. 



NEMATODE PARASITES OP RODENTS— HALL. 



87 



1858c/ Oxyuris ohvelata (Riidolphi, 1802) Dujardin, 1845, in part, 

 of various authors. 



Specifc diagnosis. — Oxyuris (p. 65) : There are three 

 very simple lips surrounding a triangular mouth aper- 

 ture which communicates directly with the esophagus, 

 the lumen of wliich is also of triangular, though larger, 

 cross section. Xo i^apillae appear to be present, prob- 

 ably because they are obscured by the inflated cuticle 

 of the head. The esophagus is somewhat clul)-shaped, 

 as usual, but is thinnest in its middle portion. The 

 terminal esophageal bulb is elongate oval instead of the 

 customary subspherical in shape. The cuticle of the 

 head (fig. 103) is inflated, the inflated area presenting 

 either a clear or granular appearance. There are two 

 characteristic cervical alae; these are prominent and 

 terminate at the level of the esophageal bulb in a re- 

 curved margin, the angle formed by this margin and 

 the lateral border of the membrane being acute and 

 slightly produced (fig. 101). Occasionally lenticular 

 thickenings of the cuticle occur on the dorsal aspect 

 near the posterior end of the cervical alae (fig. 105). 

 The cuticle is transversely striated. 



Male 2 to 2.5 mm. long and 155 to 175 [x thick. 



Head, including the inflated cuticle, 65 to 90 [jl in 



diameter. The esophagus, exclusive of the esopha- 

 geal bulb, is 195 to 225 [jl long, wdth a maximum 



thickness of about 45 [x. The 



ovoid bulb is about 115 jjl long 



and 75 to 80 [x thick. The nerve 



ring is 85 to 115 [jl from the 



anterior end of the body. The 



anterior portion of the intestine 



is greatly dilated and is reflected 



about the posterior portion of 



the esophageal bulb to form a 



depression in which the end of 



the bulb lies. The rectum is an 



elongate structure, about 95 to 



110 ]}. long, tapering from a 



broad base to the cloacal aper- 

 ture. The bursa (fig. 106) is 



very narrow, somewhat serrate 



or scalloped along its border, and 

 incised in the vicinity of the cloaca, the posterior and shorter portion 

 extending from this region to the tip of the tail. The maximum 



Fig. 103.— Oxy- 

 uris TETEAP- 

 TERA. Female, 

 e n large d. 

 After Molin, 

 18616. 



Fig. 104.— Oxyuris tet- 

 eaptera. Anterior ex- 

 tremity. X 92.5. 



