70 



ON THE GEOGRAPHY OF ANIMALS. 



caterpillar-catchers (Ceblepyrinte) : two species have 

 been detected, in both of which the males differ mate- 

 rially from the females.* Interesting, therefore, as is 

 the ornithology of Mexico, in demonstrating the transi- 

 tion from the zoological tribes of Northern America 

 to those of the Southern, nature has not, as it were, 

 paused on her route, and given animal forms to this 

 region, which she has withheld from the adjoining. 

 There is no distinction between the geographic groups of 

 Mexico, and those of the countries to which it is united : 

 the genera are common to both; the peculiarity con- 

 sists in finding these genera intermixed in one and the 

 same spot ; and exhibited in the form of species, which 

 appear, for the most part, restricted to the American 

 isthmus. The following table of the genera of birds 

 hitherto discovered in Mexico, will better illustrate 

 our meaning. 



(98.) The genera of birds characteristic of South 

 America, found in Mexico, but either unknown, or 

 only represented by one species (*) in North America, 

 are as follows : — 



Prionites III. Motmot. 

 Trogon L. Trogon. 

 Harpya Cuv. Harpy Eagles. 

 Polyborus Vieil. Carracara Eagles. 

 Cassicus D. Hangnest. 

 Tanagra Sw. True Tanagers. 

 Pyranga neil. Red Tanagers. 

 Psittacus i. True Parrots. 

 • Psittacarus Sw. Parrakeets. 



Macrocercus Fieil. Mackaws. 

 Xiphorhynchus Stir. Creepers. 

 Crotophaga L. Ano-birA 

 Tiaris Stv. Crestfinches. 

 Cynanthus Sw. Fork-tailed Hum. 



ing-Birds. 

 Lampomis Sw. 



mi ng- Birds. 



Even -tailed Hum. 



(99-) The genera more peculiar to North America, 

 found also in Mexico, but which, with few exceptions 

 (marked *), are unknown in South America, are the 

 following : — 



Setophaga Sw Fantailed Warblers. 

 Seiurus Sw. Wagtail Warblers. 

 Sialia Sw. Blue Robins. 

 Sylvicola Sw. Titmice Warblers. 

 Vermivora Stv. Worm . eating 

 Warblers. 



Pipilo J'ieil. Groundfinch. 

 * Ammodramus Sw. Sandfinch. 

 Stumella Fieil. Crescent Starling. 

 Colaptes Sw. Ground Woodpecker. 



(100.) To state the result in a more popular form, 



• See ZooL lUus. 2. pL 62. 102. 



