INTRODUCTION. 
THE enumeration of the Aves of Mexico and Central America was commenced in 
September 1879 by the late Osbert Salvin and myself, and is now completed in 
four Volumes, three of text and one of plates. Salvin’s long-continued ill-health, and 
sudden death in 1898, greatly retarded the conclusion of the Third Volume, which 
was subsequently finished by me with the assistance of Dr. R. Bowdler Sharpe 
and Mr. Ogilvie-Grant. On this account, too, it has been decided to abandon all 
idea of a Supplement, and to close the volumes as they stand. ‘The critical 
examination of the large amount of additional material that has come to hand 
during the progress of publication, and the analysis of the extensive literature on the 
subject issued in recent years, could only have been dealt with satisfactorily with the 
assistance of Salvin himself, and I am reluctantly compelled to leave this portion of 
the subject untouched. It may be noted, however, that the additions are mainly 
amongst the Passeres, which were completed in 1892. 
The physical features of the whole region are described in the Preface to the 
“Lepidoptera Rhopalocera,” concluded in 1901, and in the Appendix to the Botany, 
published in 1887, and need not be again repeated here. This Introduction will 
therefore be chiefly devoted to some remarks on geographical distribution, to the 
journeys made by us in Central America, and the sources from which our material 
has been obtained, concluding with a Table showing the distribution of the Families 
and Species as arranged in this work. ‘To make this latter as complete as possible, 
the additional countries whence specimens were subsequently received are, however, 
specially indicated. 
In dealing with the Birds we have extended the limits of our region, so as to include 
the Revil'agigedo Islands on the Pacific side (on account of the numerous sea-birds 
inhabiting them); the Island of Old Providence on the Atlantic side (this small island 
