1869.] ON THE GENUS MICRASTUR. 367 
5. MIcRASTUR LEUCAUCHEN. 
Falco leucauchen, Temm. PI. Col. 306. 
Micrastur leucauchen, Strick. Orn. Syn. p. 123. 
Micrastur gilvicollis (adult.), Pelz. Orn. Nov. p. 10. 
Hab. Brazil; Bahia (Wucherer) ; Mato Grosso (Natt.). 
This Micrastur is immediately distinguishable from M. ruficollis 
by its grey back and by the entire absence (in the adult bird) of any 
rufous colouring upon the throat and breast. In specimens not quite 
mature there is a rufous tinge upon the breast, which has apparently 
caused the species to be confounded in most collections with M. 
rujicollis. As in the latter bird, the belly is regularly banded con- 
tinuously down to the crissum. This character and its paler upper 
surface serve to distinguish it from M. gilvicollis. 
In his ‘ Planches Coloriées’ (no. 306) Temminck has figured his 
Falco leucauchen, which has been regarded by most writers as being 
the young of the same author’s Falco xanthothorax (= Micrastur 
ruficollis, Vieill.). Temminck does not expressly say whether his 
figure was taken from a specimen in the Paris Museum or in that of 
Vienna, both of which he states contain examples of this bird; 
but according to Schlegel (Musée des Pays-Bas, Astures, p. 51) 
Temminck’s type is one of Natterer’s specimens now in the Leyden 
Museum. To determine positively whether Temminck’s figure is 
applicable to the young of the present species or to that of M. rufi- 
collis, reference must be made to this type specimen, which we have 
not yet had an opportunity of doing. But to avoid the unpleasant 
necessity of giving a fresh name to the present bird, which is certainly 
a most distinct species, we propose for the present to use Temminck’s 
name for it, bearing in mind that M. Pucheran, a very accurate ob- 
server, has stated that in his opinion naturalists have erred in consi- 
dering Temminck’s two names synonymous*. 
Three specimens of this Hawk, in the collection of Salvin and 
Godman, are from Bahia, and were received from Dr. Wucherer. 
An example which we regard as the adult, and of which we shall 
speak subsequently, was obtained by Natterer in Mato Grosso. 
6. MicrasTuR GUERILLA. 
Micrastur guerilla, Cass. Proc. Ac. Phil. iv. p. 87, et Journ. Ac. 
Phil. vol. i. p. 295, t. 40; Bp. Consp. Av. p. 30. 
Micrastur concentricus, Scl. P. Z. S. 1856, p. 285. 
Micrastur gilvicollis, Scl. et Salv. Ibis, 1859, p. 218; Scl. P. Z. S. 
1858, p. 96; Scl. P. Z. S. 1860, p. 96; Lawr. Ann. L. N. Y. vii. 
. 317. 
Micrastur xanthothorax, Scl. P. Z. 8. 1859, p. 368. 
Hab. Mexico, Jalapa (Cassin) ; Cordova (Sallé); Guatemala 
(Salvin) ; Veragua (Arcé) ; Western Ecuador, Nanegal (Fraser). 
We have long been well acquainted with this Micrastur ; Salvin 
obtained specimens of it in every stage of plumage during his expedi- 
tions to Guatemala, and it is also common in Mexican collections ; 
* Rev. Zool. 1850, p. 91. 
