NO. 5 MAMMALS OF PANAMA — GOLDMAN 25 



Panama, but reappears in the western part of the republic where 

 Saimiri brstedii is a common species. In Sciurus hoffmanni is pre- 

 sented a remarkable case of discontinuous distribution of a species. 

 This common squirrel, living at high and low elevations in Costa 

 Rica and western Panama, appears to be excluded from similar 

 regions throughout eastern Panama, but specimens from Colombia 

 seem indistinguishable from Costa Rican examples. Eastern 

 Panama, it may be noted, is occupied by another common species, 

 Sciurus gerrardi, which also has a wide altitudinal range and 

 apparently similar habits. The complementary ranges of these 

 squirrels in the republic, together with the peculiar distribution of 

 sciurus hoffmanni, suggests antagonism in ecological relations. 

 Some species, like the two widely dispersed raccoons, Procyon lotor 

 and Procyon cancrivorus, reach the Canal Zone from opposite direc- 

 tions, but do not pass far beyond it. Several genera have closely 

 allied representatives which are apparently restricted to upper slopes 

 of high mountains of the eastern and western parts of the republic 

 respectively. Examples of such species are Peromyscus pirrensis 

 and Peromyscus ftavidus, Oryzomys pirrensis and Oryzomys devius. 



LIFE ZONES 



Owing to the lack of general knowledge of living forms, as well 

 as of detailed topography of the country and the local distribution 

 of life in Panama, any attempt to delimit life zones at this time must 

 be regarded as provisional. The region as a whole is highly diversi- 

 fied in character, and the number of species of animals and plants to 

 be met with at any given locality is extraordinary. While some 

 generalizations may be based on the field work already accomplished, 

 it is obvious that much more extensive investigations will be neces- 

 sary before the territory will be adequately known. 



Three life zones, or belts, are recognizable in the republic, extend- 

 ing at low elevations from sea to sea, and at higher elevations as 

 belts on the slopes, or embracing the tops of mountain ranges. 1 

 Beginning at sea level these are the Lower Tropical Zone, of which 



1 The life zones of tropical America, in their general bearings, have been 

 discussed with Dr. Frank M. Chapman, of the American Museum of Natural 

 History, whose special field of study is northwestern South America. 

 Dr. Chapman's work is based on the birds, and it is gratifying to find that, 

 although working independently, we are substantially in accord regarding the 

 number, approximate boundaries, and appropriate nomenclature of the zones. 

 The same general laws clearly apply to the areas studied by Dr. Chapman and 

 myself. 



