154 PUPILLA, AMERICAN. 



V. Australia: species 33 to 35. 

 VI. Tertiary fossils: species 36 to 51. 



Paleontology. --Pupilla appeared in the Upper Oligocene 

 of central Europe, and in the Miocene became somewhat 

 numerous. The species are referable to the section Primi- 

 pupilla, and resemble the African group of P. fontana. A 

 few Miocene forms are sinistral (P. blainvilleana, P. stein- 

 heimensis}. Forms such as P. perlabiata, more like recent 

 species of northern China, are from the Upper Miocene. 



Early species of the typical section of Pupilla, the mus- 

 corum group, have been found in German Upper Miocene. 

 The teeth are somewhat well developed, as in the recent P. 

 triplicate. A list of fossil species follows the account of re- 

 cent forms. 



In the absence of Eocene representatives in western 

 Europe it appears likely that the origin and early develop- 

 ment of the genus took place in Asia, whence in the middle 

 Tertiary or earlier, Africa and Australia received their Primi- 

 pupillcc. In America P. stcrkiana stands isolated and cannot 

 be traced, but the other Pupillae appear like recent immigrants, 

 not earlier than Pliocene, the northern P. muscorum later. 

 Only the section Pupilla, a group adapted to humid, cool- 

 temperate regions, reached this continent, and they retain the 

 closest resemblance to Old World species. P. blandi and 

 especially sonorana stand close to the Alpine P. triplicata. 

 P. hebex resembles the European cupa and alpicola. Finally, 

 P. muscorum in New England and Canada is indistinguish- 

 able from those of northern Europe. The Rocky Mountain 

 and loess muscorum may perhaps be older immigrants. 



I. NORTH AMERICAN SPECIES. 



While the American species of Pupilla appear distinct 

 enough from one another typically, they vary remarkably in 

 teeth, crest and size, so that the identity of a particular lot 

 is sometimes in doubt, The key to species cannot be trusted 

 implicitly. Thus, there are intermediate forms between 

 sonorana and blandii, and the pitkodes form of blandii has 



