140 DISTRIBUTION OP PUPILLIDAE. 



Cylindrovcrtilla, Melanesia and tropical Australia. 

 Lyropupa, Hawaiian Islands. 

 Pronesopupa, Polynesia, Hawaii. 

 Pupoidopsis, Polynesia, Hawaii. 



All of these are more or less closely related to genera occur- 

 ring in Eurasia. There is no trace of Antarctic elements sug- 

 gesting dispersal via Antarctica. 



Of the 38 genera of Eurasia, 30 genera (18 of them Recent) 

 occur in the western division of the Palaearctic Region, and 

 about 15, all Recent, in the Oriental Region; 8 of these not 

 in the Palaearctic. It is evident that old centers or areas of 

 evolution are in both southeastern Asia and in the European 

 subregion; but the presence of such Oriental genera as 

 Nesopupa, SinalUnida and Microstele in European Tertiary, 

 and Truncatellina in Chinese Tertiary and in the Riukiu curve, 

 is evidence that Tertiary exchanges of genera were more ex- 

 tensive than have taken place under the strongly differentiated 

 climates of post-Tertiary time. 



Few if any of the extinct Tertiary genera now known are 

 generalized or synthetic types. The main evolution of the 

 group seems to have been in the Paleocene and Cretaceous, 

 and still remains to be recovered. The European Oligocene 

 and Miocene pupillid fauna appears to be about as specialized 

 and mature as the Recent, and contains many genera and sub- 

 genera still widely spread. 



In no other family of land snails are the genera so widely 

 distributed as are some of the genera of Pupillidae, such as 

 Oastrocopta, Pupilla, Pupoides and Nesopupa. The data may 

 be found in the lists on following pages, but the ranges and 

 probable lines of dispersal of several genera are illustrated in 

 figures 5 to 8, pages 142 and 143. These nearly world-wide 

 ranges are an evidence of the antiquity and the great con- 

 servatism of the groups. Many of the genera of this family, 

 as of most others, are restricted to single zoological regions 

 or to smaller faunal divisions. 



Figures 5 and 7 represent the distribution and probable 

 routes of dispersal of two genera of northern origin, the dotted 



