96 



Recent Lileratnrc. [January 



'Relation of a Biological Surve}' to Agriculture.' The strictly ornitho- 

 logical poitions are : 'List of Birds noted at the Grand Caiion of the 

 Colorado, Arizona, September lo to 15, 1SS9' (pp. 38-41), embracing 57 

 species ; and an 'Annotated List of Birds of the San Francisco Mountain 

 Plateau and the Desert of the Little Colorado River, Arizona' (pp. 87- 

 lor), comprising 150 species. 



The work here under review is unique in its conception and methods, 

 and of far-reaching importance in its results. Besides the discovery of 

 many new species of mammals, and several new species of reptiles and 

 plants, a systematic and tletailed survey was made of the life zones of an 

 isolated mountain peak, rising from the edge of an arid desert — a plateau 

 region 7,003 feet above tlie sea — to an altitude of nearly 13,000 feet. In 

 ascending "from the hot and arid desert of the Little Colorado to the cold 

 and humid summit of the mountain no less than seven zones are encoun- 

 tered, each of which may be characterized by the possession of forms of 

 life not found in the others." Each is discussed in detail, its characteris- 

 tic animals and plants enumerated, and its relation to other faunal areas 

 considered. Beginning at the summit is an 'Alpine Zone' (extending 

 down to 11,500 feet), characterized by the prevalence of Arctic plants 

 and a few Arctic animals, many of them circumpolar, not found at oicii- 

 nary levels south of the tundras and barren grounds, and at interxening 

 points onlj- on the tops of the highest mountains. Below this is a 'Sub- 

 Alpine or Timber-line Zone' (between 11,500 and 10,500 feet), likewise 

 characterized by boreal forms of life, which, however, range much further, 

 south than the species characterizing the Alpine Zone. Below this is the 

 'Hudsonian or Spruce Zone,' corresponding to the so-called Hudsonian 

 Fauna of boreal North America (northern New England to Labrador). 

 Below this, in descending order, are the 'Canadian or Balsam Zone'; the 

 'Neutral or Pine Zone'; the 'Piiion Zone"; and the 'Desert Zone.' These 

 are strikingly illustrated in a colored 'diagrammatic profile," forming 

 plate I of the accompanying illustrations. 



From the study of the life zones of San Francisco Mountain, the author 

 passes to 'Generalizations concerning the Distribution of Life in North 

 America.' As recognized more or less vaguely by previous writers, the 

 present life of the North American continent is derived primarily from 

 two sources, a northern and a southern, the former circumpolar, the 

 latter tropical. The extratropical portion of North America is divided 

 into two primary life regions, a "Boreal" and a "Sonoran or Mexican 

 table-land" region. On Dr. Merriam's 'Provisional Biological Map of 

 North America showing tlie principal Life Areas' (Map 5), there are : (i) 

 An Arctic division, limited at the southward by the beginning of fort st 

 vegetation. (2) A Boreal Province, extending obliquely across the conti- 

 nent from New England and Newfoundland to Alaska, with prolongations 

 southward along the principal mountain ranges. This nearly coincides 

 with what has been sometimes termed the Cold Temperate Region. (3) 

 A Sonoran Province, occupying the region intervening betweeit ihe 



