INTRODUCTION. 11 
the whole of the Botany (5 volumes), and nine Parts of Archeology had been issued : 
since then 74 Parts (142-215) of Zoology, completing 39 more volumes, and 8 Parts 
of Archeology have been required, to bring these subjects to aconclusion. It 
was with a heavy heart that I took up my pen again. With the assistance of 
Mr. G. C. Champion I continued Vol. II. of the Rhopalocera and finished it in 1901, 
and in 1904 Vol. III. of the ‘ Aves’ with the help of Dr. R. B. Sharpe, of the British 
Museum, was also completed. 
Salvin had made a special study of the Procellariide, a very difficult group of birds, 
and for a long time we had missed no opportunity of adding specimens of Petrels to 
our collection. After writing the catalogue of this family for the British Museum, he 
intended to publish an illustrated monograph on the subject, and for that purpose 
40 plates had already been drawn by Keulemans. It remained for me to carry out 
his intention, and having again sought the aid of Dr. R. B. Sharpe we completed 
the work in 1910, enumerating 123 species, and illustrating them with 106 coloured 
plates. 
It will be seen that the travels of Salvin and myself covered only a comparatively 
small part of Mexico and Central America, but we employed a considerable number 
of expert collectors to travel in districts we had not visited, and they continued to send 
us the results of their labours for some years after we had left. Amongst them 
must specially be mentioned W. H. Richardson, Mr. H. H. Smith, and Mateo Trujillo, 
all of whom accompanied me while I was in Mexico, and Lloyd and Armstrong, who 
devoted their attention particularly to the Northern provinces of that country. 
In working out the Mexican Birds we found ourselves hampered for want of 
an authentically named collection of North American species for comparison, which 
did not exist in Europe at that time. In order to remedy this, I acquired the Henshaw 
collection, numbering 13,326 specimens, and this was rendered still more valuable 
through the courtesy of the authorities at the United States National Museum, 
who allowed Mr. Ridgway, the highest authority in America, to go through and 
verify all the names on the labels attached. I likewise purchased 2500 carefully 
named birds from Florida from Mr. W. E. D. Scott, 321 named specimens from 
California, Texas, &c., from Mr. C. K. Worthen, and a series of Mexican birds from 
Sefior F. Ferrari-Perez ; and these collections proved of great advantage to us. 
In a similar manner we dealt with the insects, &c. I bought H. W. Bates’s 
collection of butterflies, including those he obtained from the Amazons, as well as 
that of Herbert Druce, containing the ‘ Kaden’ types; the first set of the extensive 
series of Mexican and Central American Coleoptera amassed by A. Sallé (including the 
types of several of the older authors, and some thousands of specimens found by 
himself or by M. Boucard). I also acquired the general collection of Heteromera of 
F. Bates (22,390 specimens); a portion of Dr. J. S. Baly’s collection of Phytophaga ; 
the Janson collection of Elateride (25,000 specimens); various Reptilia, Coleoptera, &c., 
C2 
