Todd-Carrikee : Birds of Santa Marta Region^ Colombia. 101 



assuming that the east and west trend of the range would have' had 

 the same effect in lowering the life-zones throughout its length as is 

 the case at present in the Sierra Nevada. But here another factor, gla- 



FiG. 9. Range of Oxypogon, a genus of the Paramo Zone, to illustrate the 

 breaking up of the group into distinct species in the several parts of its range, 

 (i) O. stuebelii; (2) O. guerinii; (3) 0. Kndenii; (4) O. cyanolcemus. 



ciation, may have come into play. It is very probable that during the 

 Pleistocene the snow-line may have stood at a somewhat lower level 

 than today, and this would naturally have had the effect of lowering 



