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manifestations are European, the more ancient and morpho- 

 logically less perfect genera, Fruticicola, Heliomanes, etc., which, 

 being early evolved, are most widely diffused and form the 

 leading or foremost lines of advance, having spread over the 

 Mediterranean subregion and crossed the Asiatic continent, 

 overlapping and intermingling with the rear of the previously 

 evolved and retreating Euadeniate race, which the Siphonadenia 

 have supplanted in the European area, where the Euadenia 

 were formerly supreme and predominant. 



The Belogona Euadenia, which, before the advent of the 

 Siphonadeniate race, were the most highly organised and 

 dominant Helices in the world, are now a sub-dominant and 

 regressive group ; they formerly inhabited the European area, 

 but at the present day have their characteristic development 

 and metropolis in Eastern Asia, the primitive genus, Helicostyla, 

 with its simple dart apparatus, constituting the most advanced 

 section in the Eastern Hemisphere, having penetrated to the 

 tropical islands of Indo-Malaya ; a few representative species 

 still linger in the Mediterranean region and Central Asia, but 

 are being gradually expelled therefrom, while in Central Europe 

 Eulota jruticum is now the solitary representative of this formerly 

 dominant group. 



Though this group is now a waning one in the Old World, 

 it is the most dominant and highly developed one on American 

 soil, having crossed from Asia by the Aleutian bridge and in- 

 vaded North America, but, being prevented by the intervening 

 arid mountain ranges from eastward extension, spreads south- 

 wards along the Pacific slope, eventually penetrating to South 

 America and the West Indian Islands, probably reaching the 

 latter area by way of Yucatan, as the group has not yet invaded 

 the Lesser Antilles. 



The Epiphallogona are a more simply organised group, which 

 preceded the Euadenia in the evolutionary race, originating, 

 like the two preceding groups, within the European area, and 

 like them were in their time the predominant race, but were 

 compelled by their improved successors, the Euadenia, to evacuate 

 their place of origin and travel the same or similar routes which 

 the later-developed Euadenia followed, having been driven b}^ 

 them farther and farther from the evolutionary area, their 



