TAYLOR: SIGNIFICANCE OF DOMINANT EUADENIATE HELICES IN AFRICA. 289 



from each other by enormous intervals of time, is now very generally 

 accepted, and all these groups are here assumed to have primarily 

 emanated from the most active evolutionary centre, and successively 

 spread or are spreading over the whole globe ; the most ancient groups 

 which are also the most primitive in structure having the widest and 

 most discontinuous range, while the more modern groups follow in 

 the order of their evolution ; the more modern the group, the more 

 restricted, concentrated and compact the natural range, each group 

 preserving its relative position in regard to its predecessors and 

 successors. 



The accuracy of the foregoing deductions is supported by the 

 absence of any trace of the latest developed and most advanced group 

 in any regions except those now inhabited by its constituent species, 

 and establish that the characters of the group have been developed 

 within the area or region now occupied, whereas fossil representatives 

 of the earlier groups are actually known to exist in the strata of 

 regions far removed from the area they now inhabit, so that the fossil 

 evidence of their former existence in countries from which they are 

 now far distant tends to prove the truth of their migrations therefrom. 



Of these five great waves or periods of Helicidian evolution and 

 migration only three have hitherto been authoritatively recognized as 

 dominant regional groups in Africa, and the happy discovery of the 

 undoubted predominance of the Euadeniate Helices in the Belgian 

 Congo by Prof. Pilsbry has established the accuracy of the belief held 

 by myself and other students that a predominant Euadeniate centre 

 would be eventually found to exist in or near the very region where 

 Prof. Pilsbry has now clearly demonstrated its actual existence and 

 dominancy. 



To place Africa upon an equality with the other great continents of 

 the world, in respect of its Helicidian fauna, it now only remains to 

 detect there the presence of the Epiphallogonous group, which con- 

 stitutes the third great Pilsbryan wave of Helicidian life, and which 

 hitherto has not been regarded as an African group, and whose 

 discovery there would practically complete and connect together, as 

 far as physical obstacles permit, the radiating and advancing waves 

 of moUuscan life, thus tending fully to confirm the actuality of the 

 successive life waves, and also the probability of their origin and 

 emanation from a common centre. 



Curiously enough a species "truly Epiphallogonous in structure" 

 for which a new genus Haplohelix has been created, has been found 

 at an altitude of about 12,000 feet upon the slopes of Mt. Ruwenzori, 



