NO. 2131. 



NEMATODE PARASITES OF RODENTS— HALL. 



81 



Host. — Hydrochoerus hydrochaeris {Hydrochoerus capyhara) . 



Location. — Cecum. 



Locality. — Brazil. 



Schneider's (1866) statement that the eggs are without 

 depression may be taken to mean that they are symmetri- 

 cal instead of flattened in the usual fashion of O.vyuris 

 eggs. It is possible that this is the case or that the eggs 

 seen by him were not yet in a final state of development 

 or were seen in an imfavorable aspect. 



OXYURIS OBVELATA (Rudolphi, 1802) Dujardin, 1845. 



Synonyms. — Ascaris vermicular is p. maris Froelich, 

 1791; Ascai'is obvelata Rudolphi, 1802; Fusaria ohrelata 

 (Rudolphi, 1802) Zeder, 1803; Ascaris oxyura Nitzsch, 

 1821; Syphacia olvelata (Rudolphi, 1802) Seurat, 1016. 



Specific diagnosis. — Oxyuris (p. 65) : Body elongate 

 fusiform. Cuticle transversely striate and not dilated in 

 the head region. Three broad lips, each bearing a median 

 papilla on its outer face. Mouth cavity simple. The 

 club-shaped esophagus terminates in a subspherical bulb. 

 The rectum is elongate and communicates with the in- 

 testine by a valve. Two small cervical alae. The ex- 

 cretory pore lies a little posterior of the esophageal bulb. 



Male 1.6 mm. long by 115 ]j. thick. The posterior ex- 

 tremity is coiled in a spiral. The spicule (fig. 95) is 

 simple, slightly curved, and is 85 [x long and 7 [jl thick at 

 the base. The small accessory piece, situated transversely 

 posterior of the spicule, is shaped like a ploughshare and 

 is 37 ]i. long. The cloacal aperture is 210 [ji, from the very 

 narrow posterior end of the body. There are two pairs 

 of preanal and one of postanal papillae. The posterior 

 lip of the cloacal aperture has a small chitinous hook that 

 may be of use in copulation. 



Female 3.5 to 5.7 mm. long by 115 to 215 \i. thick. The 

 body terminates in a long, narrow tip posteriorly (fig. 

 96). The esophagus, exclusive of the bulb, is 255 to 330 

 [JL long by 50 to 70 [x thick. The subglobular esopha- 

 geal bulb is 85 to 100 [jl long and 75 to 110 [ji. thick. The nerve 

 ring is 100 to 130 [i. from the anterior end. The excretory pore 

 is about 480 pi from the anterior end. The anus is 515 to 705 \^ 

 from the tip of the tail. The vulva is very prominent and situated on 

 a conical cuticular prominence 540 to 740 /x posterior of the head. 

 The vagina extends posteriorly from the vulva and is an elongate 

 structure about 170 /* long. Uterine branches do not extend pos- 

 10600°— Proc.N.M.vol.50— 16 6 



Fig. 94.— Oxy- 

 uris OBESA. 

 Female. X 

 3. After 

 Die sing, 

 1857. 



