Mr. R. Ridgway on the Genus Glaucidium. 13 
analogue in just the same respects that Surnia hudsonia, 
Nyctale richardsoni, Syrnium cinereum, and Otus wilsonianus 
do from their Old-World representatives S. ulula, N. teng- 
malmi, S. lapponicum, and O. vulgaris, viz. in darker shade 
and greater area of the dark tints. The case is exactly par- 
allel; only the differences are in this instance less exaggerated. 
There can be no question that the two forms are derivatives 
from a common ancestral circumpolar stock, and that they 
have not yet become very widely differentiated, although 
perhaps now isolalated geographically. Evidence, however, 
is wanting to show that the present form extends northward 
along the Pacific coast to Alaska, so as to connect its range 
with that of G. passerinum in Eastern Siberia. It is but 
another instance of Palearctic birds finding their only Ame- 
rican representatives in the Western Province of the Nearctic 
Region, other examples of which are to be seen in the genera 
Cinclus, Nucifraga (“ Picicorvus’’), Coccothraustes (“ Hespe- 
riphona”’), Pica rustica, Cypselus (“ Panyptila’’), Falco saker, 
&c. Whether the American form is to be called G. passe- 
rinum, var. gnoma (G. passerinum gnoma is the form which I 
now prefer), or simply G. gnoma, is, perhaps, a matter of in- 
dividual taste. 
The original description by Wagler of his G. gnoma had 
been consulted by me; and it was only after a long consider- © 
ation of the question whether the term “ guttate” was in- 
tended to mean a form of spot inclining to a circular or to a 
longitudinal form, that the latter conclusion was adopted, and 
Wagler’s species accordingly identified with the streaked- 
crowned Mexican bird. ‘This conclusion seemed at the time 
the more reasonable, from the fact that the latter bird was 
extremely common where Wagler’s G. gnoma came from, 
while the bird which Mr. Sclater called G. californicum was 
at that time known to American writers only from within 
the United States, Mr. Lawrence’s specimen having been 
seen by me subsequently. In fact it is only after a careful 
reading of Wagler’s description, and comparison with spe- 
cimens of the two species side by side, and exceedingly care- 
ful weighing of all questions, that Dr. Coues and [I at last, 


