ART. 31 A NEW NEMATODE FROM THE OPOSSUM — DIKMANS 3 



placed rows. The spines disappear slightly beyond the middle of the 

 body. (PL 2, figs. 2-7.) 



The only point in which our specimen differs from Gnathostoma 

 turgidum as redescribed and figured by Travassos is in the number of 

 caudal papillae. Travassos states that there are nine pairs of caudal 

 papillae of which one pair is ventral and adanal and eight pairs are 

 lateral; of the eight lateral pairs, three pairs are preanal, two are 

 adanal, and three are postanal. Our specimen has five, possibly six, 

 pairs of caudal papillae, of which four pairs are large, pedunculated, 

 and lateral, two pairs of these being preanal and two pairs postanal ; 

 the fifth pair is located just in front of the fourth pair of laterals; 

 there may be a pair of adanal papillae placed ventrally, but this 

 could not be determined with certainty. In another specimen of 

 Gnathostoma collected from the stomach of an opossum (Bur. Anim. 

 Ind. Helm. Coll. No. 26831), only the four pairs of lateral papillae 

 can be made out with certainty. In the number of caudal papillae 

 our specimen agrees with Gnathostoma spinigerum and Gnathostoma 

 gracUe. It differs from the former in size, in the character and 

 location of the spines, and in the size of the small spicule; it differs 

 from the latter in the character of the spines. 



This nematode, of which only two. males were available for study, 

 has been called Gnathostoma turgidum provisionally in spite of the 

 difference here noted. When more material becomes available it 

 may be possible to determine whether the number and position of the 

 caudal papillae are sufficiently constant to serve as specific characters 

 of a new species. 



The remainder of the parasitic material collected from the 

 opossum consists of nematodes, trematodes, cestodes, and fleas. 



The nematodes are Physaloptera turgida, Cr-uzia tentaculata^ 

 Oesophagostomum. sp., Trichostrongylus sp., and T?^churis sp. Of 

 the last three, only females were collected, and no specific determina- 

 tion has been attempted. 



The trematodes are Neodiplostomwn lucidum, Harviostomum, sp., 

 Rhopalias sp., and Echinostomum sp. These were identified by Dr. 

 E. W. Price, of the zoological division. 



The cestodes are Mesocestoides sp. 



The fleas were determined by Dr. H.' E. Ewing, of the Bureau of 

 Entomology, as Rhopalopsyllus gwyni^ a species of a neotropical 

 genus, of which only a few records have been made in the southern 

 part of the United States. 



