68 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



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OXYURIS AMBIGUA Rudolphi, 1819. 



Synonyms. — Oxyurms amhigua (Rudolphi, 1819) Bellingham, 

 1844; Pasmlurus ambiguus (Rudolphi, 1819), Dujardin, 1845. 



Specific diagnosis. — Oxyuris (p. 65) : The usual Oxyuris shape, 

 that of a spindle greatly prolonged and attenuated posteriorly. The 

 mouth is simple and is surrounded by four 

 symmetrically arranged papillae. The pharynx 

 is armed with a tripartite, chitinized dental 

 structure. The esophagus is club-shaped, in- 

 creasing in size posteriorly, and is separated 

 from the spherical esophageal bulb by a deep 

 constriction. The bulb contains a chitinized ap- 

 paratus for the comminution of food. The 

 esophageal bulb is separated from the anterior 

 portion of the intestine by a deep constriction. 

 The intestine is a straight thin-walled tube of 

 almost uniform diameter, which is separated 

 from the rectum by a pronounced constriction., 

 The rectum is piriform and short in young 

 specimens; it is elongated in older ones. In- 

 ternally it presents a division into an anterior 

 and posterior portion. There are a number of 

 conspicuous cell structures, possibly glandular 

 in nature, in connection with the rectum. There 

 are no lateral alae, but there are sharp cuticular 

 ridges on each side of each lateral line which 

 show as distinct parallel lines on each side of 

 the body. There is a prominent transverse 

 strintion. 



Male 4.3 to 5 nun. long (von Ijinstow (1899) 

 says 2.9 mm.) and 240 to 275 [;. thick. Head 

 diameter, 55 to 60 [x. Esophagus, exclusive of the 

 bulb, 370 to 412 ]x. long and with a maximum 

 thickness of 60 to 70 [x. Esophageal bulb almost 

 spherical, 120 to 130 [jl long by 112 to 125 [jl thick. The nerve ring is 

 150 to 175 ]}. from the head end. The distance from the cloacal aper- 

 ture to the posterior end of the body is 370 to 410 [x. There is a bur- 

 sal membrane. There are five papillae in relation with the cloacal 

 aperture (fig. 76). One pair of these, commonly regarded as pre- 

 anal, is practically adanal. Another pair is postanal and very close 

 to the cloacal aperture. The other papilla, unpaired, is directly be- 

 hind the cloacal aperture. Another pair of papillae is located 130 to 

 150 IX posterior of the cloacal aperture at the point where the body of 

 the Avorm suddenly narrows to form the long, thin tail, which is 225 

 to 260 [x long (fig. 77). The spicule is 90 to 120 ^x long, simple in 



Fig. 76.— Oxyuris am- 

 BiGUA. Posterior 

 extremity of male. 

 Enlarged. After 

 VON LiNSTOW, 1899. 



