Dear Sir,

After an ineffectual search in Linnaeus, Brisson, etc., I begin to
suspect that I discern my brother's hirundo hyberna in Scopoli's
new discovered hirundo rupestris, p. 167. His description of ' Supra
murina, subtus albida; rectrices macula ovali alba in latere inferno;
pedes nudi, nigri; rostrum nigrum; remiges obscuriores quam
plumae dorsales; rectrices remigibus concolores; cauda
emarginata, nec forcipata,' agrees very well with the bird in
question; but when he comes to advance that it is 'statura hirundinis
urbicae,' and that 'definitio hirundinis ripariae Linnaei huic quoque
convenit,' he in some measure invalidates all he has said; at least
he shows at once that he compares them to these species merely
from memory: for I have compared the birds themselves, and find
they differ widely in every circumstance of shape, size, and colour.
However, as you will have a specimen, I shall be glad to hear what
your judgment is in the matter.

Whether my brother is forestalled in his nondescript or not, he will
have the credit of first discovering that they spend their winters
under the warm and sheltery shores of Gibraltar and Barbary.

Scopoli's characters of his ordines and genera are clear, just, and
expressive, and much in the spirit of Linnaeus. These few remarks
are the result of my first perusal of Scopoli's Annus Primus.

The bane of our science is the comparing one animal to the other
by memory: for want of caution in this particular, Scopoli falls into
errors: he is not so full with regard to the manners of his