582 



NATURALIST'S GUIDE TO THE AMERICAS 



Pheugopedius felix felix, happy wren. 



Thryomanes albinucha. Cabot's wren. 

 S.E. 



Henicorhina leucophrys mexicana, Mexi- 

 can wood wren. S.E. 



Nannorchilus leucogaster pacificus, Co- 

 lima wren. W. 



Nannorchilus leucogaster brachyurus, 

 Temax wren. S.E. 



Hylorchilus sumichrasti, Sumichrast's 

 wren. S.E. 



Catharus melpomene melpomene, night- 

 ingale thrush. S.E. 



Turdus tristis aasimilis, Jalapa thrush. 

 E. 



Turdus infuscatus, black thrush. S.E. 



Turdus Jlavirostris, Mazatlan robin. W. 



Myadestes unicolor, slate-colored soli- 

 taire. S.E. 



Polioptila albiventris, Yucatan gnat- 

 catcher. S.E. 



Calocitta formosa formosa, Bullock's 

 magpie-jay. W. 



Psilorhinus mexicanus mexicanus, white- 

 tipped brown jay. E. 



Psilorhinus mexicanus vociferus, Yu- 

 catan brown jay. S.E. 



Xanthoura luxuosa luxuosa, green jay. 

 E. 



Cissilopha san-blasiana pulchra, Aca- 

 pulco jay. W. 



Cissilopha yucatanica, Yucatan jay. 

 S.E. 



Cyanolyca nana, dwarf jay. S.E. 



Cyclarhis flaviventris flaviventris, Mexi- 

 can pepper-shrike. S. 



Cyclarhis flaviventris yucatanensis, Yu- 

 catan pepper-shrike. S.E. 



Vireosylva magister cinerea, Cozumel 

 vireo. S.E. 



Neochloe brevipennis, green-winged 

 vireo. E. 



Pachysylvia decurtata, gray-headed 

 pachysylvia. S. 



Diglossa baritula, Mexican diglossa. S. 



Coereba mexicana, Mexican bananaquit. 

 S. 



Granatellus venustus, Du Bus' red- 

 breasted chat. W. 



Gymnostinops montezuma, Montezuma 

 oropendola. E. 



Amblycercus holosericeus, Pre vest's 

 cacique. S.E. 



Megaquiscalus major obscurus, Colima 

 boat-tail. W. 



Dives dives. Sumichrast's blackbird. 

 S.E. 



Icterus melanocephalus melanocephalus, 

 black-headed oriole. S. 



Chlorophonia occipitalis, Mexican 

 chlorophonia. S.E. 



Tanagra hirundinacea, Bonaparte's 

 euphonia. E. 



Thraupis abbas, Abbot tanager. E. 



Piranga roseo-gularis roseo-gularis, rose- 

 throated tanager. S.E. 



Phlogothraupis sanguinolenta, crimson- 

 collared tanager. S.E. 



Phoenicothraupis rubica rubicoides, Mex- 

 ican ant tanager. E. 



Phoenicothraupis rubica affinis, Oaxaca 

 ant tanager. W. 



Chlorospingus ophthalmicus , brown- 

 headed chlorospingus. E. 



Arremonops rufivirgatus eras sir ostris, 

 Cordoba sparrow. S.E. 



Arremonops superciliosus sumichrasti, 

 Acapulco sparrow. W. 



Arremonops verticalis, Schott's sparrow. 

 S.E. 



Richmondena cardinalis yucatanica, Yu- 

 catan cardinal. S.E. 



6. Covillea Association (Lower Austral 

 Zone}. With Covillea glutinosa as a 

 convenient plant indicator this zone, 

 also characterized by many other 

 peculiar plants and many animals, 

 occupies much of the northeastern part 

 of the Republic, including the lower 

 portions of the tableland region in the 

 interior, the Rio Grande Valley, the 

 coastal plains of Sonora, and the central 

 section of Lower California from lati- 

 tude 30 to near La Paz. 



This zone, lying next the Tropical 

 Zone, is separated from the latter by 

 the normal frost line. In it occur 

 representatives of a considerable num- 

 ber of animals and plants of groups 

 mainly tropical in distribution which 

 may be regarded as intrusive, and have 

 become specifically or subspecifically 

 differentiated. It is an area of great 

 aridity and includes the dryest sections 

 of North America. While the zone as a 

 whole is distinguished by the general 

 occurrence of Covillea and other widely 

 ranging ligneous species these are locally 

 very irregularly distributed and inter- 

 rupted by sections of grassland, espe- 

 cially along the bottoms of broad val- 

 leys, by sand dunes, usually of limited 

 extent, and by streams bordered by 

 vegetation with a high moisture require- 

 ment. These and other locally varying 

 environmental conditions favor the 

 development of minor plant and animal 

 associations or communities of limited 

 extent. 



