PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 



613 



those which appear to have radiated from the Antillean Continent are 

 indicated by the letter A. 



Unionidce, Megaspiridce, 



Pleuroceratidce, Urocoptidce A, 



Viviparidce, Testacellidce, 



Diplommatinidce, Zonitidce, * 



Cyclostomatidce A, Limacidce, 



Proserpinidce A, Arionidce, 



Lymnceince, Philomycidce, 



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. Achatinidce. 



Etheriidce. Aperidce. 



Ampullariidce. Rhytididce. 



Chilinidce. Streptaxidce. 



Acavidce. Circinariidce. 



Strop hoc heilidce. Veronicellidce. 



Bulimtilidce. 



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 Autochthonotis Families of Eogceic Origin. 

 Circinariidce. Northern South America and temperate North America. 

 Bulimulidce. Autochthonous ; formerly spread to Australasia and now 



invading North America. 

 Strophocheilidce. 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 Casnogaeic faunas. 



