326 



BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



Male 10 to 16 mm. long by 350/* wide. Tail (fig. 391 a and b) 

 curved ventrally. Cloacal aperture 320 to 400/* from tip of tail. 

 Four pairs of preanal and 2 pairs of postanal papillae. Smit says 

 there are 2 to 4 pairs of postanal papillae, but apparently figures 2 

 pairs of preanal papillae. Two unequal spicules ; one is 3 to 3.5 mm, 

 long by 8 to 10/* wide, the other is 200 to 220/* long by 30/* wide. 

 In Smit's specimens the long spicule was 480/*. long and the short one 

 150/* long, according to his description, but, taking the width of the 

 worm as a basis for size in his illustrations, these measurements ap- 

 pear incorrect, and the relative lengths of the spicules as figured do 

 not agree with his measurements. 



Female 12 to 19 mm. long by 430/* wide. Anus 400 to 530/x from 

 tip of tail (fig. 390). Vulva 1 to 1.4 mm. from tip of tail. Vagina 



/avyu. 



Pig. 389. — Oxyspirura mansoni. a, Dorsal view and b, front view of head; c, 



EGG; d, EMBRYO ESCAPING FROM THE EGG. (C.O.r., CIRCUMORAL CUTICULAR BING ; 

 es., ESOPHAGUS ; Lp., AMPHIDS OR SO-CALLED " LATERAL PAPILLAE " ; Jrt, MOUTH ; 

 ph., PHARYJVX ; S.l.p., SUBLATERAL PAPILLAE; S.m.p., SUBMEDIAN PAPILLAE.) AFTER 



Ransom, 1904 



1.5 to 2 mm. long. Eggs (fig. 389 c and d) oval, 50 to 65/* by 45/* 

 (Smit says 40/* long by half as wide; see O. parvovu??i, p. 328). 



Larva, first stage, 225 to 250/* long by 12/* wide. Esophagus 50/* 

 long. Head end rounded. Tail end terminates in a thick, blunt 

 appendix. 



Life history. — Unknown. The eggs produced by the female worm 

 wash down the tear ducts and are swallowed, passing out in the 

 droppings. The fact that the eggs will hatch in 2 to 3 days under 

 favorable conditions suggests that the eggs are not ingested im- 

 mediately by a secondary host, but that there may be a secondary 

 host which is infected by larvae, the larvae developing to adults in 

 the body of the primary host when these secondary hosts are swal- 

 lowed by it. Emmerez and, later, Ransom were unable to find 

 either eggs or larvae in the eye, and Ransom and, later, Wilcox and 

 McClelland fed larvae without obtaining infection in the primary 

 host. According to the latter authors larvae develop to a length of 



