ART. XV. -THE GEOGRAPHICAL DISTRIBUTION OF THE MAM- 

 MALIA, CONSIDERED IN RELATION TO THE PRINCIPAL 

 ONTOLOGICAL REGIONS OF THE EARTH, AND THE LAWS 

 THAT GOVERN THE DISTRIBUTION OF ANIMAL LIFE. 



By Joel Asaph Allen. 



I.— DISTRIBUTION OF MAMMALIAN LIFE IN THE NOETH- 

 ERN HEMISPHERE, CONSIDERED IN RELATION TO LAWS 

 OF GEOGRAPHICAL DISTRIBUTION. 



When, ia 1871, I published* a few preliminary remarks concerning 

 the general subject of geographical zoology, it was my intention soon to 

 present more fully the facts whereon were based the few general princi- 

 ples then stated. In this paper I claimed, in accordance with the views 

 of Humboldt, Wagner, Dana, Agassiz, De Candolle, and others, that life 

 is distributed in circumpolar zones, which conform with the climatic 

 zones, though not always with the parallels of the geographer. Sub- 

 sequent study of the subject has confirmed the convictions then ex- 

 pressed. These are directly antagonistic to the scheme of division of 

 the earth's surface into the life-regions proposed by Dr. Sclater in 1857, 

 based on the distribution of birds, and since so generally adopted. 

 Their wide acceptation, it seems to me, has resulted simply from the 

 fact that so few have taken the trouble to sift the facts bearing upon 

 the subject, or to carefully examine the basis on which Dr. Sclater's 

 divisions are founded. The recent appearance of Mr. Wallace's labori- 

 ous and in many respects excellent and praiseworthy workt has now 

 rendered a critical presentation of the subject more necessary than be- 

 fore, since, instead of seeking in the facts of geographical zoology a 

 basis for a natural scheme of division, he has unhesitatingly accepted 

 Dr. Sclater's ontological regions and marshalled his facts and arranged 

 his work wholly in conformity with this, as I shall presently attempt to 

 show, grossly misleading scheme. The source of error, as I hope to make 

 evident, lies in method of treatment. Assuming apparently that the 

 larger or continental land-areas are necessarily coincident with natural 

 ontological regions, divisions of the earth's surface wholly incompara- 



* On the Geographical Distribution of the Birds of Eastern North America, with 

 special reference to the Number and Circumscription of the Ornithological Faunae. 

 <Bull. Mus. Comp. Zool., vol. ii, No. 3, pp. 375-450. April, 1871. 



+ The Geographical Distribution of Animals. With a Study of Living and Extinct 

 Faunas as Elucidating the Past Changes of the Earth's Surface. By Alfred Russel 

 Wallace. Two vols. 8°. With maps and illustrations. London, 1876. 



Bull. iv. No. 2 1 313 



