I02 NATURAL SCIENCE. Aug.. 



Turkey, and Greece shall have been ornithologically explored and 

 the results described in the complete American fashion ; when the 

 first collection of birds arrives from Timbuktu ; when Arabia 

 gives up its ornithological secrets ; and when the parts of Siberia 

 and Asia, of which nothing is yet known, have been explored ; 

 to say nothing of the high mountain interiors of many of the 

 Malayan islands ; then — and scarcely till then — shall we be able to 

 generalise with some chance of success. 



This deficiency in our information, however, need not prevent us 

 from hazarding an idea — as has, indeed, often been done before now — 

 of some of the avi-geographical regions of the Old World, and I place 

 before my readers the divisions which I introduced into my Royal 

 Institution lectures, leaving it for future statistics to confirm or 

 destroy my conclusions. I begin, therefore, with the New World, 

 adopting, for the purposes of my lectures, the old divisions of the 

 Nearctic and Neotropical Regions : — 



A. — Nearctic Region (Northern Region of the New World). 

 I. Arctic Sub- Region. 

 II. Alaskan Arctic Sub-Region. 



III. Aleutian Sub-Region. 



IV. Cold Temperate Sub-Region. 

 V. Warm Temperate Sub-Region. 



1. Humid Province. 



a. Appallachian Sub-Province. 

 /3. Austroriparian Sub-Province. 



2. Arid Province. 



y. Campestrian Sub-Province. 

 S. Sonoran Sub-Province. 



B. — Neotropical Region (Southern Region of the New World). 



I. Antillean Sub- Region, including the Greater Antilles and 

 Southern Florida, as also the Lesser Antilles, with the exception of 

 Trinidad, Tobago, and the islands off the coast of Venezuela. 



II. Central American Sub-Region. 



1. Mexican Province. 



2. Isthmian Province. 



Until my friends, Messrs. Salvin and Godman, have finished 

 their monumental " Biologia," it will be impossible to define 

 accurately the boundaries of the several provinces, especially as 

 fresh facts are being brought to Hght every day. A division may be 

 hazarded on the lines of Mr. Salvin's conclusions published in the 

 Proceedings of the Zoological Society for 1867 (pp. 131, 2) and 1870 

 (pp. 177, 8). Thus we shall probably get two provinces, which may be 

 called : — 



I. The Mexican Province, including Central America from 

 Costa Rica northwards to Mexico, leaving out the Central Plateau, 



