'S92.] ^ Recent Literature. 38 1 



prefer to assign it definitely to one or the other of the contiguous regions, 

 and if called upon to make the assignment we should with little hesitation 

 add it to the so-called 'Sonoran' Region, with which on the whole it seems 

 to be most closely related. 



In this connection we would reiterate our protest (see Auk, VIII, p. 

 9S, last part of last paragraph) against the use of the term trciNsitioNal as a. 

 specific designation for any faunal area of whatever grade or character. 

 Until nature devises some means of erecting hard and fast barriers ab- 

 ruptly limiting the habitats of animals, there must be between any two 

 contiguous faunal areas a belt of neutral or transitional territory, more or 

 less marked according to circumstances. The Hudsonian Zone, for ex. 

 ample, is a 'transition' zone between the Arctic and Canadian, or at least 

 its northern half may be so considered, while the Lower Sonoran Zone is 

 likewise 'transitional' between the Tropical Region and the Upper Sono- 

 ran ; and so on. 



" The Tropical Region reaches the United States at two remote points — 

 Florida and Texas. In the former it exists as a narrow subtropical belt 

 encircling the southern half of the Peninsula from Cape Malabar on the 

 east to Tampa Bay on the west. In Texas it crosses the Lower Rio Grande 

 from Mexico and extends north to the neighborhood of the Nueces River. 

 In western Mexico the Tropical Region reaches Mazatlan" (p. 33). 



Dr. Merriam considers his subject especially from the standpoint of mam- 

 mals, and tabulated lists of the genera and species distinctive of the dif- 

 ferent zones and life areas are given. Yet his consideration of the subject 

 is by no means limited to this class of animals, but relates as well to plants 

 and land animals in general. After passing in review the special subject 

 of his address, he devotes considerable space to the consideration of gen- 

 eral subjects, discussing at some length the influence of the glacial period 

 upon the present character and distribution of life in North America and 

 the origin of its present fauna. He also considers the causes controlling 

 distribution, and emphatically identifies himself with the long list of emi- 

 nent authorities who believe that the solution of the whole question may 

 be found in climatic conditions. In this connection attention is called to 

 Mr. A. R. Wallace's assumption that temperature has comparatively slight 

 influence upon the distribution of animal and vegetable life, and especially 

 to his various misstatements and erroneous assumptions respecting the dis- 

 tribution of life in North America and the limiting effects of mountain 

 barriers to its distribution. In commenting on the so-called 'Nearctic' and 

 'PaltEarctic' Regions of Sclater, he shows that of the 31 'boreal' genera o» 

 North American mammals 77 per cent are common to Boreal America and 

 Boreal Eurasia. Facts of similar import are cited in reference to insects. 

 In conclusion Dr. Merriam observes: "I see no reason why a homoge- 

 neous circumpolar fauna of great geographic extent should be split up into 

 primary regions possessing comparatively few peculiar types simply be- 

 cause a water separation happens to exist in the present geologic period ; 

 nor is it evident why one of the resulting feeble divisions should be 



