2248 The Zoologist — August, 1870. 



sparse and scanty marbling to a nearly uniform black, particularly 

 upon the breast, and is therefore not to be too implicitly relied upon, 

 at least until it is more definitely ascertained than at present whether 

 the black mottling tends to decrease or to increase with advancing 

 age. If microceros grows more and more marbled with black as i 

 grows older, we might with entire propriety presume upon the 

 existence of a youthful state of plumage, in which the under parts are 

 entirely white, like those of pusillus. Such is very likely the real 

 state of the case ; for the youngest examples of microceros examined — 

 those which have no trace of a tubercle — are nearly white below, only 

 very sparsely and indistinctly mottled with blackish. Still, aside 

 from all these varying and therefore uncertain points, there appear 

 good grounds for separating the two species, as will be observed on 

 comparing the descriptions given in this and in the preceding 

 article. 



As the case stands with our present information upon the subject, 

 P. pusillus is to be separated from P. microceros : first, by certain 

 differences positively known to occur ; a, in size, which is decidedly 

 less, as evidenced by the measurement of all its dimensions; b,in 

 form of bill, w liich is slenderer, more acute at the tip, not so deep at 

 the base, particularly not so wide at the base, yet not shorter, than 

 that of microceros : secondly, by certain differences very commonly 

 observed, yet not proven to always hold good ; a, absence of tubercle ; 

 b, conspicuously white scapulars and tips of secondaries; c, pure 

 white under parts, uninterrupted b}' blackish mottling, and extending 

 around on the sides of the neck ; d, shortness and scantiness of the 

 white setaceous feathers on the forehead ; e, colour of bill, mostly 

 black, not mostly red. 



It only remains to notice the synonymy of this species; and all 

 that is to be said on this score relates to the identification of Alca 

 pygmaja, Gni. This name is founded upon the "Pigmy Auk" of 

 Pennant, — a small species first described very loosely and imperfectly 

 by the latter writer, whose account Gmelin merely renders into Latin 

 in applying a binomial name. There is no doubt that the bird was 

 one of the little auks of the North Pacific, as its very name, and the 

 dimensions assigned (seven inches), clearly indicate, but there is no 

 possibility, at the present day, of identifying it with precision. It was 

 very possibly based either upon the present species or the preceding 

 (microceros), and should these two ever be united, as young and old 

 pf the same, the name pygmsea might without undue violence be 



