252 PARASITES OF THE DOMESTIC ANIMALS 



The species is parasitic in the stomach and small intestine of the hog. 



2. Physocephalus sexalatus (Spiroptera sexalata). Filariidie (p. 

 244). — The body is subcylindrical and slightly'- tapering anteriorly. The 

 head is made distinct by a cuticular inflation extending to the posterior 

 end of the pharynx. The mouth has two three-lobed lips, each lobe 

 having a rounded papilla and leading into a small buccal capsule. The 

 cylindrical pharynx has a spiral band which usually breaks up into 

 separate rings in the middle of its course and again becomes spiral toward 

 the posterior end. The body of the male is nearly uniform in diameter. 

 The caudal extremity is twisted spirally and has narrow membranous 

 wings which are symmetrical. There are eight pairs of papillae, of which 

 four pairs are preanal and stalked, the postanal papillae small, with 

 short stalks, and close to the tail. The spicules are very unequal. The 

 body of the female is thickest near the anus, terminating abruptly in a 

 blunt point furnished with a small conical tip. The vulva is posterior to 

 the middle of the body. 



Length of female, 13-19 mm. (1/2-3/4 of an inch). In the region di- 

 rectly anterior to the anus the width is 333-450 microns. The male is 

 6-9 mm. (3/16-11/32 of an inch) in length. 



The eggs are oval, 34 by 15 microns, slightly flattened at the poles, 

 and thick-shelled. They contain well-developed embryos at the time of 

 oviposition. 



The species is parasitic in the stomach and small intestine of the hog. 



In neither of these two species is the life history known. The thickness 

 of the egg-shell indicates that the embryos are not released until this is 

 acted upon by the gastric juice of the host, and, therefore, that develop- 

 ment occurs without an intermediate host. 



In a report upon his investigations of these worms published in 1912, 

 Foster, of the Zoological Division of the Bureau of Animal Industry, 

 gives the following summary: 



"Two species of roundworms belonging to the family Filariidae, of 

 particular interest to helminthologists and veterinarians on account of 

 their wide distribution and frequency of occurrence in American swine 

 and the possibility thai they may cause serious injury to their host, are 

 given special consideration in this paper. 



"One of these species, identified as Spiroptera strongylina, has re- 

 cently been placed in a new genus, Arduenna, of which it is the type, 

 and several errors regarding the anatomy of this parasite have been 

 corrected. Another species, Arduenna dentata, has been found in China 

 associated with Arduenna strongylina, and, although not yet reported in 

 American swine, is mentioned in this connection, as further investiga- 

 tion may reveal its presence in this country. 



"Arduenna strongylina is much more common in American swine than 

 it is said to be in European swine, and has been found abundantly in 



