ART. 16 HELMINTH PARASITES OF THE OPOSSUM CHANDLER 13 



virginiana in Louisiana. This specimen, he says, agrees in general 

 with Travassos's redescription of G. turgiduvi^ but like mine differs 

 in the number of caudal papillae. His specimen agrees with mine 

 in this respect and is undoubtedly specificall}^ identical. Dikmans 

 provisionally considered his forms to be G. turgklum until more 

 material became available to determine the constancy of the number 

 and position of the caudal papillae. The material here described 

 supplies this need and makes it evident that the species he was dealing 

 with is not G. turgidum but a distinct species, which is identical with 

 the one here described as G. dklelphis. It should be pointed out, in 

 passing, that G. horrldmiv^ described by Leidy (1856), from the lumen 

 of the stomach of an alligator, may also be identical with G. d'ldel- 

 phis. It is described as being 2% inches long and a line and a half 

 thick (3 mm), anteriorly covered with palmate plates furnished 

 with as many as eight spines and degenerating posteriorly to simple 

 spines. As Baylis and Lane (1920) pointed out, it is quite likely that 

 this worm was really parasitic in some animal, probably a mammal, 

 which wa,s devoured by the alligator. The large size may have been 

 due in part at least to the relaxation of a dead or dying worm, which 

 was beginning to decompose. The mention of eight spines on the 

 scales as a maximum, however, leaves the specific identity of this 

 worm with G. didelphis open to question. It is unlikely that the true 

 identity of Leidy's Avorms will ever be known. G. gracile (Diesing, 

 1838) is another gnathostome, found in the stomach of a large carniv- 

 orous fish, which probably did not belong in the animal in which it 

 was found, but it is clearly distinguished from either of the opossum 

 species {G. turgulum and G. dldelphis) by having only five points 

 on the body spines. 



All the gnathostomes which I obtained, about a dozen of them, 

 were found burrowing in the liver of an opossum. The liver was 

 severely damaged by the burrowing of the worms and presented the 

 same appearance as that of livers of cats infected with immature 

 Gnathostoma spinigerum,^ as described by Chandler (1925a). In the 

 case of these worms the larval forms, differing from the adults in 

 having only four rows of head spines and in having the body scales 

 represented by minute denticulations. burrow through the walls of 

 the digestive tract after cysts containing the larvae are eaten, and 

 enter the liver from the peritoneum. As shown by the writer 

 (1925b), the worms grow to several times their original size and 

 then assume the adult morphology, presumably following a molt. 

 Some of these sexually immature adults were found still burrowing 

 in the liver, while others had left the liver and were found in the 

 mesentery, diaphragm, and stomach wall. It seems evident that in 

 G. spinige'i^m, the stomach is invaded by the parasites from the 



