32 THE ROUNDWORMS OF DOMESTIC SWINE. 



In his description of Physocephalus, Von Drasche (1884a) suggests 

 the possibility that Schneider's (1866a) Filaria nitidulans may be 

 identical with P. sexalatus. Both worms are characterized by three 

 lateral wings on either side, and the caudal extremity of the males of 

 both species are alike in the number and arrangement of the papillae. 

 The measurements of Filaria nitidulans (males 20 mm., females 32 

 mm.) are, however, far in excess of the measurements for Physo- 

 cephalus sexalatus, and the position of the vulva of Filaria nitidulans 

 is stated as "directly above the anus," while the vulva of Physo- 

 cephalus sexalatus is slightly posterior of the middle of the body. 

 Ciurea (1912), who has recently reexamined Schneider's material, was 

 unable to determine the location of the vulva of F. nitidulans. He 

 gives, however, a summary of the differences between Filaria nitidu- 

 lans and Physocephalus sexalatus, proving conclusively that they be- 

 long to different species, although he considers that Filaria nitidulans 

 should be included in the genus Physocephalus. Stossich (1897b), fol- 

 lowing Von Drasche's (1884a) suggestion, considered the worms 

 identical. He listed Tapirus americanus as a host of Physocephalus 

 sexalatus and combined Molin's (1860b) measurements of P. sexalatus 

 with Schneider's (1866a) measurements of Filaria. nitidulans. 



DISTRIBUTION OF ARDUENNA STRONGYLINA AND PHYSOCEPHA- 

 LUS SEXALATUS IN THE UNITED STATES. 



Of nine lots of Arduenna strongylina collected in various parts of 

 the United States and now deposited in the helminthological collection 

 of the Bureau of Animal Industry, only two have been found not to 

 contain examples of Physocephalus sexalatus, and both of these lots 

 contain only a few specimens. The distribution of Arduenna strongy- 

 lina is therefore similar to that of Physocephalus sexalatus, since the 

 latter species, according to the writer's experience, is practically always 

 associated with the former. 



To determine the distribution of these parasites and the frequency 

 of their occurrence in the United States the literature was searched 

 for references to Spiroptera strongylina. Four such references were 

 found, as below; in most cases Physocephalus sexalatus was probably 

 also present but not recognized. 



1. Curtice (1892g), in a list of parasites infesting domestic animals 

 and man in the United States, includes the following entry : "Spiroptera 

 strongylina. Hud. Host, Sus scrofa domestica. Location, stomach," 

 followed by the remark, "Is often found with the food and attached to 

 the walls." Specimens No. 2058 of the helminthological collection of 

 the Bureau of Animal Industry were collected and identified by Cur- 

 tice as Spiroptera strongylina. These specimens have been examined 

 by the writer, who verified Dr. Curtice's identification. A few exam- 

 ples of Physocephalus sexalatus were also present. 



