ART. 17 PARASITES OF AMPHIBIA AND REPTILIA HARWOOD i 



pared with Diplodiscus subclavatus, the type species of Diplodiscus, 

 important differences appear. In D. subclavatus the testes are single 

 except in very young specimens ; the vitellaria extend in two groups 

 from the pharyngeal region to the caudal end of the intestinal ceca ; 

 and the posterior sucker has a cavity in its center instead of a promi- 

 nence with special musculature. In the North American forms there 

 is never any indication of fusion of the testes; the vitellaria are 

 arranged in two or four compact groups with the anterior follicles 

 scarcely reaching the level of the anterior testis; and the posterior 

 sucker has a prominence with special musculature. These seem to 

 me to be rather fundamental differences and to justify the placing 

 of the North American forms in a separate genus. The name 

 Megalodiscns Chandler (1923), proposed for his species americanus, is 

 available for these North American forms. Diplodiscus temperatus 

 Stafford and D. intermedins Hunter become Megalodiscus temperatus 

 (Stafford) and M. intermedins (Hunter), respectively. Megalodiscns 

 americanns stands as the type species of the genus. Opisthodiscus 

 americanus Holl and Megalodiscus ranophilns Millzner fall into 

 synonymy with M. temperatus. 



Genus MEGALODISCUS Chandler, 1923 



MEGALODISCUS AMERICANUS Chandler, 1923 



A single specimen taken from the rectum of Rana sphenocephala 

 is tentatively referred to this species. The testes are relatively some- 

 what larger than any of Chandler's specimens of M. americanus^ and 

 they overlap more. These are minor differences, and in view of the 

 limited material and wide host ranges known to exist among amphi- 

 stomes, there seems to be no justification for its separation into a 

 new species. 



MEGALODISCUS TEMPERATUS (Stafiford. 1905) 



Stafford described this species from frogs. It is widely distrib- 

 uted in these animals in eastern North America. I have taken it 

 from Rana sphenocephala^ R. catesheiana^ R. areolata^ R. clamitans^ 

 and Pseudaci^s triseriata^ at Houston, and from the first two hosts 

 mentioned and Hyla cinerea at Huntsville, Tex. 



The above account, besides adding to our locality records, includes 

 four new hosts. 



The material from the A^arious hosts presented such a variety of 

 appearances that I at first thought a number of species were present, 

 but on careful examination it was impossible to find any constant 

 charact-er by which to separate any new species. The five specimens 

 from Pseudacris triseriata were barely 1 mm long, yet eggs were 



