371 REVIEWS. 



species, we have a right to demand that he should sa}^ what a spe- 

 cies is. But this is all we have : — "The question of species and 

 of specific synonymy is simplified to this : that whenever two forms 

 which have both received specific names are found to intergrade, 

 the more recent name shall become a synonym of the older." (p. 

 245.) Simple and easy as this seems, it presents great if not 

 insuperable obstacles ; and we will add just here, that this shifting 

 of the question from the vital point, namely, the discussion of 

 what a species is, to a superficial issue, namely, the propriety of 

 imposing names upon this or that form, is not what we should 

 have expected from a naturalist of Mr. Allen's position. 



Following his rule we hold our nomenclature by a frail tenure 

 indeed ; for nothing in biology is more certain than that the mul- 

 titude of animals and plants now existing, are the ramifications of 

 comparatively few trunks ; and nothing is more unstable than iu- 

 tergradation which he proposes as a crucial test. To speak roundly, 

 everything runs into soraething else ; not necessarity just now (though 

 this is frequently the case), but at some period. "Species," like 

 some plants, are stoloniferous ; they produce offsets that finally 

 separate from their parent stock, and appear like distinct entities. 

 Our x)ositive specific forms — those that alone we should recognize, 

 according to Mr. Allen — are simply those whose wide divergence 

 has concealed or broken their connections with the original stem ; 

 while all debatable forms (and these constitute a great part of our 

 lists) are merely those that are in A'isible process of separation. 

 When a form has diverged to the slightest appreciable degree, 

 some ornithologists, like Brehm, for instance, label it with a bino- 

 mial ; most ornithologists, probably, wait till they think that this 

 divergence is a settled thing not likely to revert ; but nearty all 

 will name with the connecting links before their eyes. Mr. Allen, 

 however, like Prof. Schlegel, would virtually ignore the pro- 

 cess of divergence, until it has reached a certain, or rather an un- 

 certain, point, and effaced connections that once existed. We 

 are opposed to this, and still plead for names, if only as "conven- 

 ient handles for facts" that it is of the last importance to bear in 

 mind. Pure synonyms are pure trash, of course, and none detest 

 them more cordially than ourselves ; but we insist upon the advis- 

 ability, in the present stage of our science, of recognizing geograph- 

 ical and some other differentiations by name. * No stronger 



•Not necessarily a " speoiflc " name, but some one additional word, with or without 

 AMER. NATURALIST, VOL. V. 24 



