20 ^Fr. H. Seebohm on Messrs. Blakiston and Fryer's 



the days of Liimseus to those of Wallace and Darwin most 

 ornithologists were agreed that species were divided by a hard 

 and fast line, and that the difficulty which the student had 

 to surmount was the discovery of the lines of demarcation 

 which nature herself had drawn between the various specially 

 created species. Now that most scientific ornithologists have 

 adopted the theory that these hard and fast lines seldom exist 

 in nature^ that species were not specially created but were gra- 

 dually developed according to certain more or less known fixed 

 laws, and that consequently there must be at any one period 

 of the workVs history a large number of species in process of 

 diflFerentiation^ our difficulties are largely increased. The 

 question naturally arises, What is a species ? We must 

 either draw an artificially hard and fast line where nature 

 has drawn none, or we must accept nature as she is, and make 

 the best of the complications which necessarily arise in our 

 nomenclature in attempting to harmonize it with facts which 

 we cannot, as scientific students, ignore. Hence it appeal's 

 to me to be absolutely necessary for modern ornithologists to 

 recognize the existence of subspecies — that is, species in the 

 process of difierentiatiou, incipient species, where the inter- 

 mediate forms have not yet died out, but Avhere a series gra- 

 dually leading from one extreme to the other may be obtained. 

 I fully recognize the danger of such a practice. It is easy to 

 imagine the abuses of which it is capable. Inexperienced 

 ornithologists will be tempted to think that diflferences of age, 

 sex, and season, to say nothing of accidental individual varia- 

 tions, are intermediate forms worthy of the rank of a sub- 

 species ; and our nomenclature may run the risk of being still 

 more flooded M'ith names as injurious as the useless synonyms 

 of the elder Brehm. I am, however, of the opinion that 

 these difficulties will have, sooner or later, to be faced. It 

 seems to me that the scientific ornithologist cannot afford 

 any longer to ignore the existence of subspecies in nature, or 

 to attempt to make ornithological nomenclature simpler than 

 the facts of nature which it is intended to discriminate. 



Another point to which I wish to call the attention of or- 

 nithologists is the recognition of subgenera. The non- 



