204 TRANSACTIONS OF THE HORTICULTURAL 



illustrate our meaning we will take the Vireos. of whom Dr. Coms 

 reckons thirty species, many of which vary so little from each other 

 that the most minute scientific examination of specimens is necessary 

 to determine to which species they actually belong. Of course their 

 identification as living birds is quite impossible when such critical 

 examination of specimens becomes necessary. These species can be 

 distinguished from others most unlike them, but few of them can be 

 certainly so distinguished from those nearest them in points of des- 

 c-ription. 



t)n this point we quote from Dr. Coms" Key to North American 

 Birds, page 118. " Genus Vireo. — The numerous species of this 

 genus have been divided into several groups, but no violence will be 

 done by considering them all as vireos — in fact, it is difficult to do 

 otherwise. For even the seemingly substantial divisions into two 

 genera, according as there is an evident spurious first primary, or ap- 

 parently none, separate species, like g Urns n.\\A philach^Jplucus^ hardly 

 otherwise specifically distinguishable: while another division into 

 two genera according to shape of the wings and length of the spuri- 

 ous first primary, or its absence, is subject to some uncertainty of 

 determination, and unites species like oliraceiis undffarlfroKS, most 

 dissimilar in other respects. The fact is, that almost every species of 

 Vireo has its own peculiar form, in shape of bill, proportions of pri- 

 maries, etc., and these details cannot be considered as of more than 

 specific value." 



Tn the above extract Dr. Coms (one of the best authorities) 

 evidently disapproves of making such slight variations into generic 

 differences, and more than intimates a doubt whether such slight 

 differences should separate c/ilnis and 2)hila(hlpln'cui^ into distinct 

 species. Science should be exact in its premises and its deductions, 

 leaving no room for doctors to disagree ; and in so far as it falls 

 short of that exactness it is not science. 



What does the spurious primary above referred to indicate but 

 a degree in evolutions between the primary and its absence. If so, 

 it seems hardly worth while to dignify each degree of change in the 

 progress from one fixed type to another, (if that can be properly 

 called fixed which is changing from type to type), by naming it a 

 new genera, or, on .slight differences, a new species. The answer to 

 this query will depend on the ascertained practical aid or hinderance 

 to identification to be derived from the minuteness of these subdi- 

 visions used in classification. There are stages in every science dur- 

 ing which each new discovery is hailed as an onward step, entitling 

 the discoverer to a higher plane than any hitherto occupied. This 

 condition of things has its advantages as leading to much that is new 

 and valua])le in science. On the other hand it has its disadvantages 

 as leading to the introduction of errors, which must be eliminated. 



If the identification of birds depended wholly upon the distinc- 

 tive differences noted by the eye, we should be more often puzzled 



