292 Dr. J. H. Blasius on the Diversity in the Estimate 
XXX.— On the Diversity in the Estimate of the European Ornis, 
and its Causes, By Dr. J. H. Blasius*. 
It appears to me to be desirable that, from time to time, we 
should ascertain the point which we have attained by our 
joint endeavours. It is absolutely necessary that we should 
ascertain clearly what we are to regard as positively gained, and 
what we have to leave to the future as problems still to be 
solved. Our circumstances, our environments indicate to us as 
an important part of our endeavours the elucidation of European 
ornithology. 
No land on the face of the earth has been more repeatedly 
examined than Europe. We often hear, and, indeed, we might 
justly suppose, that the ornithology of Europe is quite settled; 
but every one who possesses an accurate knowledge of the sub¬ 
ject must declare this assertion to be a manifest error. In no 
branch of ornithology—neither in systematic division, nor in 
literary criticism, nor in the observation of modes of life, nor in 
oology—has complete agreement, certainty, or peace been arrived 
at. To refer to one only of these points, that of the systematic 
division and enumeration of species,—for nearly forty years, no 
single scientific investigation, perhaps, has led to such divergent 
results as this with regard to European ornithology. 
We find enumerated in— In the year Species. 
Brehm, ‘ Lehrbuch * . 
1823 ... 
.... 471 
Bonaparte, 4 List/ &c. 
1838 ... 
.... 503 
Temminck, ‘ Manuel/ 2nd edit. 
1840 ... 
... 499 
Keyserling and Blasius, ( Wirbelthiere ’ . 
1840 .., 
.... 484 
Schlegel, ‘ Kritische Uebersicht ’. 
1844 .., 
.... 489 
Thienemann, f Rhea ’. 
1846 ... 
.... 470 
Degland, ‘ Ornithologie ’ . 
1849 ... 
.... 507 
Bonaparte, 4 Revue Critique * . 
1850 ... 
.... 539 
Brehm, ‘ Naumannia * . Tt 
1855 
950 
and with the subspecies 
....1628 
Brehm, e Vogelfang’. 
1855 .. 
....1030 
and with the subspecies 
....1800 
Bonaparte, ‘ Catalogue Parzudaki ’ . 
1856 .. 
.... 581 
De Selys-Longchamps, 4 Revue de Zoologie ’ ... 
1857 .. 
.... 509 
Keitel, 4 Verzeichniss/ &c. 
1857 .. 
.... 501 
Des Murs, £ Traite d’Oologie * . 
1860 .. 
.... 536 
* This important paper is translated from the Report of the Thirteenth 
