440 General Notes. [£" k 



blue mussels (Mytilus edulis) and barnacles (Balanus balanoides) , the same 

 diet, and same resort, as that of the Turnstone (Arenaria interpres morin- 

 ella). — Arthur H. Norton, Portland, Maine. 



Hybridism and Generic Characters in the Trochilidse. — I am tempted 

 to offer a few comments on Mr. Walter P. Taylor's interesting article in 

 the July 'Auk,' not merely because the subject is one to which at the 

 present time I am giving special attention, but because I believe there is 

 much to be said against Mr. Taylor's view of the case. Before discussing 

 the question of generic differences, however, I wish to correct an error 

 (for which I seem to be responsible) concerning the type-locality of Selas- 

 phorus floresii. This is given as "Bolanos, State of Oaxaca," whereas it 

 should read Bolanos, State of Jalisco; therefore, the supposed fifth speci- 

 men mentioned in the second paragraph on page 292 is the same example 

 as that on which the supposed species was based. There is not the slightest 

 doubt in my mind that this bird is a hybrid of Selasphorus rufus or S. 

 alleni and Calypte anna, and it is not improbable that all four of the 

 known specimens are of California origin, for I have an indistinct rec- 

 ollection of having somewhere read that some of Floresi's specimens were 

 obtained in California and subsequently, through error, labeled Bolanos. 1 



Concerning generic distinctions it will simplify the matter very much 

 to state that the question hinges entirely on what constitutes a genus in 

 birds, and especially in the Trochilidse. The generally accepted definition 

 of a genus in zoology and botany is a group of species which agree in the 

 possession of certain characters not possessed by any other species or group 

 of species. In the various definitions of a genus which I have consulted 

 in connection with this article, 2 it is nowhere implied that the differences 

 must be exclusively morphological; the implication being that it is only 

 necessary that a given group or set of species should share in certain ob- 

 vious characteristics which separate them from any allied group. Every 

 one knows that taxonomic groups, whether generic or of higher rank, are by 

 no means of equal value in all classes of vertebrates (see footnote on page 

 6, 'Birds of North and Middle America,' Part I), and that birds, as a 

 Class, are so very much more uniform in structure, and at the same time 

 so much more numerous in species than the members of any other Class 

 that, necessarily, a more minute subdivision is required, or, in other words, 

 orders, families, genera, etc. (all super-specific groups), while arbitrarily 

 equal in taxonomic rank are by no means (and cannot be) based on char- 

 acters of equal anatomical importance. It is unfortunate that this fact is 

 sometimes lost sight of, and that some would require for an avian genus 



1 If I am not mistaken in this impression, a similar case is that of several speci- 

 mens in the National Museum collection received from Mr. John Xantus and labeled 

 by him " Plains of Colima " which were undoubtedly obtained in California. 



2 See Agassiz, Essay on Classification, § 5, Standard Dictionary, Century Dic- 

 tionary, etc. 



