70 Annals of the Carnegie Museum. 



miles of arid and semi-arid country on both ends. As a result of this 

 isolation we find that this area, although in fact more humid in char- 

 acter than the forest section east of the Cienaga Grande, has fewer 

 typical representatives of the Humid Tropical than the other. In 

 order to bring out this difference more clearly, the following figures, 

 based on a careful tabulation of the species recorded at Fundacion and 

 Tucurinca on the one hand, and at Don Diego and Dibulla on the 

 other, are presented herewith: 



Number of species listed 220 



Fundacion and Tucurinca 167 



Don Diego and Dibulla 134 ' 



Common to both regions 82 



Representative forms in each region 2 



It appears, therefore, that out of 167 species observed in the region 

 of Fiindacion only half extend to the humid region of the north 

 coast, while only about forty per cent of the avifauna of the latter 

 reach the other — a circumstance which is significant indeed. On the 

 other hand, there are a number of forms which, although normally 

 confined to the Piedmont belt, habitually drop down to sea-level in 

 this north coast region, such as Oreopeleia violacea albiventer, Phae- 

 thornis striigularis striigularis, Pipra erythrocephala erythrocephala, 

 Tyranniscus chrysops minimus, Hapalocercus meloryphus, and Micro- 

 cerculus squamulatus corrasus. 



Faunal Affinities. — With this review of the local distribution we 

 are now ready to discuss the larger question of the origin and rela- 

 tionships of the fauna of the Tropical Zone of the Santa Marta region 

 as a whole. Obviously it is a composite fauna, made up of two 

 different elements, mingled in varying proportions. Only towards 

 the east, in the arid plains of the Goajira Peninsula, and including also 

 the upper Rio Rancheria-Rio Cesar Valley, where the conditions are 

 known to be very similar, is there a practically homogeneous fauna. 

 Here we get the following forms, all of which, except those marked 

 with an asterisk, are otherwise confined to Venezuela: 



Eupsychortyx cristatus cristatus *Hypnelus ruficollis decolor 



*Ortalis ruficrissa Chlorostilbon caribous 



*Psittacula passerina cyanophanes Leucippits fallax fallax 



Thectocercus hcemorrhous neox- Poecilurus candei venezuelensis 



enus *Synallaxis albescens perpallida 



