400 Letters , Announcements , fyc. 
few birds probably ascend to a height o£ 2000 feet in the air, 
the vulture tribe excepted. Nearly the whole of its animated 
inhabitants are likely to be as distinct as its plants. Is it 
peopled with human beings ? Who can tell ? Why not ? 
The summit, Mr. Brown says, is inaccessible, except by 
means of balloons. Well, that is a question to be settled on 
the spot between an engineer and a first-rate f Alpine 3 . .. . . 
But put it that a balloon is required, surely it would be worth 
while for one of our scientific societies to organize a balloon 
expedition for the purpose. No one can tell what problems 
in natural science might not be elucidated. We have here 
an area of limited extent, within which the secular variation 
of species by natural selection, if any, must have gone on un¬ 
disturbed since, at least, the very beginning of the present 
age in the world's life. Can there be a fairer field for the 
testing of those theories which are occupying men's minds so 
much in our days ? " 
We hear with great pleasure that a young ornithologist, 
already known to fame (Mr. Everard E. im Thurn), has re¬ 
ceived the appointment of Director of the Natural-History 
Museum at Georgetown, Demerara, with liberty to travel 
and explore for a certain portion of the year. We trust he 
will turn his attention to the mysteries of Roraima. 
Translation of Muller’s Memoir on the Voice-organ of the 
Passeres .—We are glad to be able to announce the approach¬ 
ing publication, by the Delegates of the Oxford University 
Press, of a translation, by Mr. Bell, of Muller's Classical Essay 
upon the organs of voice of the Passeres. Prof. Garrod has 
undertaken to supply a series of notes to bring the work up 
to the level of our present knowledge of this important sub¬ 
ject. The Academy of Berlin has most liberally granted the 
use of the original copper-plates, to which, however, we be¬ 
lieve, additions will be made. 
