70 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



155 /i. 

 body. 







The nerve ring is 190 to 215 /* behind the anterior end of the 

 From the anus to the end of the tail is 2.34 to 4.51 mm., of 

 which the thin, solid terminal portion is 

 190 to 210 iJL. The vulva is 1.54 to 1.89 mm. 

 from the anterior end. The vagina extends 

 far posteriorly and then branches, sending 

 two uteri forward. Eggs of typical 

 Oxyuris shape, flattened on one side, 95 to 

 103 [JL long by 43 p, thick in utero. (Von 

 Linstow's measurements of 130 by 53 ^ are 

 probably for the eggs as oviposited.) 



Hosts. — Oryctolagus cuniculus {Lepus 

 cuniculus), Lepus europaeus {Lejyus tim- 

 idus), Lepus arcticus {Lepus glacialis), 

 Lepus species, Syl/vilagus floridanus mal- 

 lurus. 



Location. — Cecinn and large intestine. 

 (Von Linstow (1899) lists it from " Cav. 

 abdom.") 



Localities. — Germany, Austria, United 

 States (Washington, District of Columbia; 

 Bethesda, Maryland; Nebraska; Detroit, 

 Michigan). 



Life history. — Probably direct and sim- 

 ple. Eggs oviposited in morula stage.' 



Schneider (186G) states that this species 

 has a lateral membrane broadened on its 

 free edge to form a T-shaped cross section. 

 I am unable to verify this. So far as I can 

 determine the only lateral meml)rane is that 

 indicated by the cuticular ridges bounding 

 the lateral lines.- These might suggest a 

 T-shaped cross section on focusing. 



Dujardin (1845) makes this species type 

 and only species of the genus Passalurus. 

 The genus is apparently based on the mouth 

 armature. I have retained it in Oxyuris 

 on its general conformity. See Addendum, 

 page 224. 



OXYURIS EVOLUTA von Linstow, 1899. 



Synonym. — Oxyuris evaginata Smith, 1908. 



Specif c diagnosis. — Oxyuris (p. 65) : Body of typical Oxyuris 

 shape, the female showing the prolonged posterior extremity. There 

 are three large broad lips (fig. 80) and between them three other 

 intermediate lip structures projecting nearer to the median longitu- 

 dinal axis. Posterior and median of these and forming an anterior 





% 



"pwr 



Fig. 79.— Oxrmiis ambigua. 



A PORTION OF THE POSTERI- 

 OB EXTREMITY OF THE FE- 

 MALE. 



