296 Dr. J. H. Blasius on the Diversity in the Estimate 
Falco peregrino'ides, T. 
-sparverius, L. 
Haliaetus leucocephalus, L. 
Ulula nebulosa, Forst. 
Caprimulgus atrovirens, Laud. 
-climacurus, Vieill. 
-virginicus, Briss. 
Hirundo senegalensis, L. (ca- 
pensis, Gm.). 
Pams atricapillus, Gm. 
-bicolor, L. 
Troglodytes fumigatus, T. 
Uragus sibiricus, Pall. 
Corvus dauricus, Pall. 
-ossifragus, fVils. 
Peristera semitorquata, Gm. 
-lugens, Rupp, (risoria, L.). 
Eurynorhynchus pygmaeus, L. 
Ardea herodias, L. 
Buphus russatus, T. 
Pelecanus mitratus, Licht. 
Dysporus melanurus, T. &c. 
It would be a just requirement of the ornithological public 
from its writers, or of the latter from themselves, that they 
should only admit positively ascertained species into the fauna 
of Europe, and finally consign ascertained errors to oblivion. 
This certainly does not offend against any internal conviction, 
or against a principle carried out to its consequences. The 
question regards only a vacillation between a mere external 
scrupulous completeness in name, or simple, non-critical care¬ 
lessness, and positive adherence to fact. 
It is only when we remove the whole of the exotic species, or 
at least those which have been erroneously admitted, that we 
can see clearly how far the different numbers of the summary 
above given are caused by diversity of fundamental views, by 
mutually opposed principles or requirements. 
If we deduct the whole of the exotic species observed occa¬ 
sionally in Europe, there remain in 
Thienemann, * Rhea ’. 
Keyserling and Blasius, 4 Wirbelth.’ 
Schlegel, 4 Krit. Uebersicht* . 
Brehm, 4 Lehrbuch * . 
Bonaparte, 4 Revue Crit.’ . 
Des Murs, *'Traite’ . 
Bonaparte, 4 Catalogue P.’ . 
Brehm, ‘ Vogelfang ’. 
401 species 
424 
430 
450 
463 
466 
500 
940 
and with the subspecies 1700 ,, 
as regular inhabitants of Europe. There is no essential change 
in the proportions above given; the statements vary from double 
to quadruple the average number. Here also occurs again the 
same abrupt and irreconcileable opposition of the majority of 
