PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 613 



those which appear to have radiated from the Antillean Continent are 

 indicated by the letter A. 



Unionidcz, Megaspiridce, 



Pleiiroceratidez, Urocoptidce A, 



Viviparidce, Testacellidce, 



Diplommatinida, Zonitida, x 



Cyclostomatidce A, Limacidce, 



Proserpinidce A, Arionidce, 



Lymnceince, Philomycidcz, 



Helicidce, Oleacinidce A. 



Clausiliidce, 



III. Eogceic or Southern fauna, which occupied chiefly the Gondwana 

 continent, including a large part of South America, tropical and south 

 Africa, and stretching in a great arch, possibly at no time perfect, to penin- 

 sular India and Australia. Here were evolved the families : 



Mutelidce. Acltatinidce. 



Etheriidce. Aperidce. 



Ampullariidce. Rhytididcz. 



Chilinidcz. Streptaxidcz. 



Acavidcz. Circinariidtz. 



Strophocheilidcz. Veronicellidce. 



Bnlimulidcz. 



The South American fauna is largely made up of groups of typically 

 Eogaeic or Southern origin, but there are also northern forms, derived 

 from Middle America (" Antillia"), and a few groups of ancient and 

 unknown origin. These several elements are as follows. 



I. PRIMITIVE GROUP. 



Families of very Ancient and Unknown Origin and World-wide Distribu- 

 tion, and Isolated Autochthonous Families of Eogaic Origin. 

 CiYcinariidce. Northern South America and temperate North America. 

 Bulimulidce. Autochthonous ; formerly spread to Australasia and now 



invading North America. 

 Strophocheilidcz. Autochthonous. 

 Endodontidce. World-wide, on all continents and islands. 



1 Primitive Zonitida were probably evolved at a very early time, but the group attained its main 

 development in the Caenogaeic faunas. 



