The Zoologist — August, 1870, 2247 



are very conspicuously white ; the secondaries plainly tipped with 

 white ; the under parts pure white, unspotted as in typical pusillus. 

 The black of the upper parts is tinted, especially about the head, with 

 gray or plumbeous, and there are no traces of whitish setaceous 

 feathers on the forehead ; both of which features are to be attributed 

 to the juvenility of the specimen. The doubt in the case centres in 

 the bill. This organ has no trace of a tubercle, and is very small and 

 weak, as usual in the young pusillus ; but it seems to be deeper, and 

 especially wider at the base, compared with its length, than is the case 

 with typical pusillus; in these points of shape approximating to 

 microceros. But " seems to be " is the most definite expression to 

 be used in this case, for in the preparation of the specimen, or its 

 subsequent drying or packing for transportation, the bill has been 

 injured, and so much distorted, that its true form cannot now be 

 determined with desirable precision. 



It cannot be denied that the relations that this species bears to 

 microceros are extremely intimate. So closely, in fact, does it 

 approach the latter, that its specific validity might fairly be called in 

 question by one of conservative views ; especially in consideration of 

 the well-known fact, not to be disputed, that the bills of all young 

 Alcidse are much smaller and weaker, and even in more striking points 

 of form, conspicuously different from those of adult birds ; and that a 

 long time is required for their perfect development. This remark 

 applies with especial force to the formation of the various knobs, 

 ridges, sulci, rictal callosities, and the other irregularities of surface. 

 The mere presence or absence, therefore, of the node upon the base 

 of the culraen, cannot be allowed to constitute a specific character in 

 the present case, and may be left out of consideration, as may be, also, 

 the colour of the bill. Too much stress should not be laid upon the 

 presence of white scapulars and of white tips to the secondaries, since 

 in some specimens of undoubted microceros unmistakable traces of 

 the former are to be found, and the ends of the inner secondaries are 

 decidedly lighter than the body of the feathers. All the observable 

 diff'erences in the quantity and distribution of the whitish setaceous 

 feathers upon the forehead and other parts of the head might readily 

 enough depend upon a difference in the age of specimens. The pure 

 uninterrupted white of the under parts of pusillus stands in apparently 

 strong contradistinction to the black mottling of the same parts of 

 microceros ; but it is to be remembered that the coloration in this 

 respect of the latter species is very variable, ranging from a very 



