74 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



Hosts. — Acanthion hrachyura {Ilystrix hrachyura) , Erethizon 

 dorsatum, Erethizon epixanthum. 



Location. — Cecum and small intestine. 



Localities. — Berlin (Zoological Collection) ; United States (Phila- 

 delphia, Pennsylvania (Zoological 

 Garden) ; Washington, District of 

 Columbia (Zoological Park) ; Wis- 

 consin). 



This species was first described by 

 von Linstow (1899) and has since been 

 noted only by Smith (1908). Both of 

 these writers had only nongravid 

 females which had attained only about 

 half of the adult size. This accounts 

 for the fact that the measurements 

 given here are in excess of those given 

 by von Linstow and by Smith. The 

 writer is fortunate in having an abun- 

 dance of material collected in 1896 by 

 Dr. Albert Hassall from Erethizon 

 epixanthum^ together with some more 

 material, in very bad shape, however, 

 sent in from Erethizon dorsatum in 

 Wisconsin in 1898. The material first 

 noted contains numerous males. 



For a similar species see the next 

 species, Oxyuris hilgerti. 



OXYURIS HILGERTI Seurat. igMcf. 



Specific diagnosis. — Oxyuris (p. 05) : 

 Cuticle transversely striated at 14 jx 

 intervals. No lateral alae. Muscle 

 cells diamond-shaped and 800 |x long. 

 Mouth with three lips (fig. 84), each 

 provided with one papilla. Buccal 

 cavity very short. Esophageal bulb 

 with denticular apparatus. Intestine 

 larger at its origin than the bulb. Two 

 prominent rectal glands. Nerve ring one-eighth of esophagus length 

 from anterior extremity. Small excretory pore opens posterior of 

 the esophageal bulb in the middle of a long clear area. Copulation 

 occurs at an early stage while the males and females are nearly the 

 same size, the females subsequently becoming mature and much 

 larger than the males. 



Male 3.8 to 6.2 mm. long and very slender. Posterior extremity 

 commonly rolled in a spiral of two turns. Length of esophagus is 



Fig. 83.— Oxyuris evoluta. Fe- 

 male GENITALIA. AFTER SMITH, 

 1908. 



