PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 



625 



autochthonous group, such as Oleacinidcs, Urocoptidce, Cerionida, Sagdincz 

 Cyclostomatidce, Helicinidce, contains many phylogerontic lines, signalized 

 by shells with more or less detached or uncoiled later whorls, sculptured 

 embryonic whorls, highly developed, often spinose sculpture, complicated 

 internal armature, and the like. These first families of Antillia, now in their 

 old age, are related to the families of the northern or Caenogaeic area of 

 land-mollusk evolution. Some of them, and the ancestors of all, doubtless 

 had a much wider range in Mesozoic times. A few, such as the Oleacin- 



FIG. 32. 



FIG. 33. 



Fie. 34. 



Distribution of Epiphal- 

 logonous Helices in America 

 (exclusive of Solaropsis and 

 Macrocydis), 



Distribution of Urocop- 

 tidse. Shaded area Eucalo- 

 diince and Holospirince ; black 

 area Urocoptince. 



Distribution of Cyclo- 

 phoridcB in America. 



idee and Cyclostomatidcs, were abundantly developed in Europe as late as 

 the Miocene, or even linger in a few forms in the recent fauna. These 

 European forms cannot, in my opinion, be looked upon as ancestral to the 

 Antillean, but rather as parallel descendants of a common stock derived 

 from the north, where the old Scandinavian and North American land 

 areas were, at least from time to time, united. 



A second element of the Mid-American lands consists of groups derived 

 from the Chinese or east-Asiatic center. Prominent members are the 

 dart-bearing and the Epiphallogonous Helicidce, the Cyclophoridcz, Dip- 



