40 
the monography of Muscicapide on which I was engaged. Of that 
collection I had already formed very high expectations; but I was 
agreeably surprised by finding them all surpassed, so great is the rich- 
ness of this noble collection. It contains more than 14,000 speci- 
mens of stuffed birds, besides skins, which are not yet numbered. 
What adds still greater interest to this collection is, that it contains 
a large number of the original specimens described by Latham and 
other English authors, of whose writings these specimens are the only 
explanation. To the pleasure of working in so rich a collection must 
be added the command of a colossal library, to which not one work 
of importance is wanting. ll this, with the aviaries of magnificent 
living birds, from every zone of the world, must have the greatest 
charm for the naturalist, and make Knowsley Hall for him a perfect 
Eden, which once seen shall never be forgotten. 
The new birds described here include only one portion of my re- 
searches, because I could not finish so many genera. The materials 
of the very rich family of Muscicapide are too extensive, for a com- 
plete elucidation during the limited period of my visit from a foreign 
country ; I wish my descriptions therefore to be considered only as 
fragments. 
The object of my visit to England was to collect materials for a 
complete monography of the Muscicapide ; but notwithstanding the 
many favours I received, and the extreme liberality with which my 
labours were facilitated in every English collection, I must confess 
with sorrow that I shall never be able to make a complete whole (per- 
fectly free from objection), with materials collected in different mu- 
seums. A perfect arrangement can only be achieved by the study of 
the materials present together, so that at every moment a compari- 
son may be made between any two or any number of the species. 
Were it my good fortune to assemble the whole materials of one 
family in my rooms at Darmstadt, one winter only would be neces- 
sary to finish each family in such a manner as to satisfy the require- 
ments of modern science. 
Were any one museum willing to accord me the whole materials in 
its possession, it is probable that all the supplementary species not 
contained in that collection would be readily furnished by other mu- 
seums, as the absence of a few species for a short period would be of 
little or no importance. 
That we can only climb to the summit of our science by means of 
well-made monographies, there can be no possible doubt ; and I attach 
a higher value to a monography constructed on philosophical prin- 
ciples, than to the best fauna of any single part of the world: for 
only by a strict comparison of the birds of the five parts of the globe 
can we know what is a family, a subfamily, genus, species and sub- 
species. Only in this way—a difficult way no doubt—can we learn 
the true harmony of nature; and thus shall we be filled with admi- 
ration, when we see that every species, genus, family or order repre- 
sents a certain type, and must receive its place in a scheme of classi- 
fication according to fixed laws, which man must discover, but over 
which he has no control. 
