462 
T)l L. SOÓS 
distinction that could be made between N. peloponnesia on the one hand, 
and N. meridionalis and N. Prevostiana on the other. 
The peculiarities seen in their geographical distribution suggest 
that they are such remnants of a species especially predominant toward 
the close of the Tertiary period as, at a subsequent colder climate, hap¬ 
pened to survive at places especially favourable to their survival. 
I also derive, as seen above, N. danubialis from this ancestral 
species, the marked modifications in form having been brought about 
by alterations in the conditions of life. 
