448 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1912. 



and there attain their maximum. Those who deny marsupial migra- 

 tion across Antarctica are obliged to assume that the Thylacinidse 

 were independently evolved in each hemisphere. That Tasmania was 

 the point of entry is supported by the discovery in Tasmania of the 

 earliest fossU Australian marsupial. This, Wynyardia hassiana, is 

 apparently one of the Phalangeridse, but the unique example is too 

 imperfect for positive identification. (Spencer, Proc. Zool. Soc. 1900, 

 p. 776.) Local geologists class the stratum in which it occurred as 

 Eocene, but English and American geologists are less disposed to grant 

 these beds such antiquity. 



If marsupials had not been available, the case could have been made 

 as clear from herpetological evidence. And, indeed, were the verte- 

 brata disregarded, the hypothesis could still be as well established 

 from the invertebrata or the plants. 



Among the reptiles, 50 genera of the Iguanidse are known, all of 

 which are confined to the New World, chiefly South America, except 

 one genus in Fiji and two in Madagascar. Australian snakes are 

 divisible into the venomous and the nonvenomous groups. All the 

 venomous are of the family Elapidas, related to South American types ; 

 they focus in Tasmania, where nonvenomous snakes are absent. The 

 nonvenomous snakes are of Asiatic or Papuan affinity, and focus in 

 North Queensland. The majority of Australian frogs are also akin 

 to South American forms. 



A family of large snaUs, conspicuous for the size and beauty of the 

 shell and distinct in structural features, called by Dr. Pilsbry the Ma- 

 croogona, has the following distribution: In South America, chiefly 

 tropical, Macrocyclis 1 species, Strophochilus 51 species, and Gonyo- 

 stomus 5 species; in Madagascar, Ampelita 54 species and Helico- 

 phanta 16 species; in the Seychelles, Stylodonta 2 species; in Ceylon, 

 Acavus 7 species ; in the Moluccas, Pyrochilus 4 species ; in Tasmania, 

 Anoglypta 1 species and Caryodes 1 species; in Eastern Australia, 

 Pedinogyra 1 species and Panda 4 species. The Chilian Marcrocyclis 

 and the Queensland Pedinogyra by shell characters pair together, 

 while Helicophanta is a match for Panda. The absence of this family 

 from New Zealand, its preponderance of species in Madagascar, of 

 genera in Tasmania with Australia, and its development in the Tropics 

 are remarkable characters of this old austral group. 



The snail family Bulimulidje is characteristic of South America, 

 beyond which two genera stray into the West Indies and North 

 America, and two others, Bothriembryon and Placostylus, occur in 

 Australasia. The first ranges from Tasmania to West Australia, and 

 forms an exception to Antarctic rule by having its distribution center 

 in the latter. Indeed, Bothreimbryon and the fluviatile crustacean 

 Chaera])s raise a suspicion that West Australia had direct relations 

 witii Antarctica prior to and independent of the Tasmanian Isthmus. 



