PREFACE. 
Wagler's frame was strong and vigorous; he was 
devoted to field-sports for the opportunities they gave 
him of observing Nature, and was an excellent shot. 
On the 15th of August_, 1832_, as he was returning 
from one of his hunting-expeditions near Munich, he 
received a severe wound from the accidental discharge 
of a gun, which, in spite of every attention, caused his 
death on the 23rd of the same month, at the early age 
of 32 years. 
Wagler worked principally on Reptiles, Amphibians, 
and Birds, and, as regards the two former classes, will 
ever be known as the author of the volume devoted to 
the Serpents in Spix^s great work on the Zoology of 
Brazil and of his own ' Descriptiones et Icones Amphi- 
biorum ' and ^ Natiirliches System der Amphibien/ 
His two principal ornithological works were a Mono- 
graph of the Psittacidae, published in the '^Trans- 
actions of the Boyal Academy of Munich^ (1832), and 
his ^ Systema Avium/ unfortunately left incomplete. 
Besides these, the six Essays which he contributed, 
in 1829 and the three following years, to the pages of 
Oken^s 'Isis^ are constantly referred to by ornitho- 
logists, whose studies will, we trust, be facilitated by 
the present reprint of them, which, except for the cor- 
rection of a few very obvious misprints, has been made 
word for word from the original. 
P. L. S. 
11 Hanover Square, London, 
Jan. Sth, 1884. 
