Mr. R. Ridgway on the Genus Glaucidium. l.'i 



analogue in just the same respects that Surnia hudsonia, 

 Nyctale richardsoni, Syrnium cinereum, and Ohcs wilsonianus 

 do from their Old- World representatives S. uliila, N. teng- 

 mahni, S. lapponicum, and 0. 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 Palsearctic 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 W^agler^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, 



