24 ORTMANN 
Ortmann, P. Amer. Philos. Soc., 44, 1905, p. 103 f.). Moreover, 
it belongs to a rather advanced and modern group of this sub- 
genus (a//enz-group), which is characteristic for the late Terti- 
ary and Post-tertiary plains of the South Atlantic and Gulf bor- 
der in the United States. Thus it is very probable, that this 
species immigrated into Mexico from the United States, repre- 
senting a direction of dispersal opposite to that generally ob- 
served in the genus, for which, however, at least one other in- 
stance is known (C. clark, 1. c., p. 126). The known habitat 
of C. wzegmanni appears rather isolated, and it is much to be de- 
sired that northern Mexico and southern Texas should be in- 
vestigated with a view to settle this question. 
The most primitive species of the subgenus Camdarellus (C 
shufeldtz) is found in Louisiana. C. chapalanus appears slightly 
more primitive compared with C. montezume and its varieties, 
and is found in western Mexico. Of the montezume forms, 
areolatus is the most primitive and the most northern, nearest to 
the United States, while occ¢dentalis is the most advanced (shape 
of rostrum), and is western in Mexico. Thus the evidence 
is partly contradictory. Leaving out chapalanus, the general 
trend of the evidence is to show that the subgenus originated in 
the southern United States and immigrated into Mexico, first 
into the central plateau, then into the Pacific slope. 
This would, consequently, offer a third case of reversed 
migration in this region, and my map (1905, pl. 3) should be 
changed accordingly (the brown color). This would also not 
conflict with the morphological characters of Cambaredlus, the 
shape of the sexual organs inclining more toward the subgenus 
Faxonius of the United States, than toward the Mexican sub- 
genera. But I must confess, that the evidence for this assump- 
tion appears at present too scanty, so that we can hardly call it 
more than a mere theory. It is chiefly with a view to instigate 
further research on these questions that I have ventured to ex- 
press at all an opinion on this topic. 
