^"^^f"^^] Recent Literature. Ill 



In considering questions of distribution the authors do not Umit them- 

 selves to a consideration of life zones but recognize " three entirely different 

 orders of ecological delimitation," which they indicate by the terms ' zonal,' 

 ' faunal ' and ' associational.' In their discussion of the zones they fail to 

 detect in the animal life any trace of either the Hudsonian or Arctic Alpine 

 which had been credited to the San Jacintos by H. M. Hall in his report 

 on the flora of the mountains, and rather question the desirability of 

 including these zones on the very meagre data that he was able to furnish. 

 The authors state that they would use the word ' fauna ' for " a subdivi- 

 sion of a life zone, based upon conditions of atmospheric humidity." As 

 has been the experience of others however they find that practically it is 

 better to use the term in a different sense, giving it in a manner a higher 

 rank than the ' zone.' For instance they recognize a Colorado Desert and 

 a San Diegan fauna each covering both the Upper and Lower Sonoran 

 Zones. The late Dr. Arthur Erwin Brown advocated precisely the same 

 plan in discussing the distribution of reptiles in Texas, and claimed that the 

 Upper and Lower Sonoran zones of the eastern humid area had far more in 

 common than either had with the corresponding zone in the arid region, 

 and he therefore made his primary divisions east and west instead of zonal. 

 Dr. J. A. Allen adopted a similar plan in his paper on ' Distribution of 

 North American Birds' (Auk, X, pp. 97-150). 



In their use of ' Associations ' the authors are recognizing the work of 

 the ecologic botanists, and they are essentially bringing out the correlation 

 of the distribution of certain animals to certain plant ' formations ' — an 

 important point and one which underlay a recent paper by Dr. Spencer 

 Trotter.i 



In their closing chapters the interesting fact is emphasized in connection 

 with boreal islands or mountain tops that " the smaller the disconnected 

 area of a given zone, the fewer the types which are present thereon," while 

 the disturbing part that this principle is likely to play in attempts to 

 estabhsh centers of distribution and lines of dispersal upon the number of 

 existing species is pointed out. The difference in the faunas on the two 

 slopes of the San Jacinto mountains — semihumid on the west and ex- 

 tremely arid on the east, is pointed out as well as the variability in the 

 extent to which characteristic forms of one fauna invade the other, the line 

 of dehmitation being by no means uniform for all species. This discussion 

 opens up very interesting lines of investigation as to the reason for the 

 different behavior of different species on the margins of their habitats and 

 the whole paper is an excellent illustration of what may be accomplished 

 in the study of distribution in limited areas with diversified physical condi- 

 tions, such as prevail so frequently in the west but are hard to find in the 

 eastern states. 



The annotated Ust of birds is a valuable one and contains much impor- 



» of. Auk, 1913, p. 450. 



