ALLEN ON GEOGRAPHICAL DISTRIBUTION OF MAMMALS. 323 



and Asiatic. One or two others barely touch, or possibly overlap slightly, 

 the above-given boundary. North of the isotherm of 36 F. not more 

 than two or three families are met with that are not cosmopolitan, and 

 two of these have each but a single species north of this line. 



The following is a list of the families referred to above, with approxi- 

 mate indications of their distribution. 



Families of non-pelagic mammals occurring north of the mean annual of 70 F. 



Summary. 



Whole number / 33 



Subcosmopolitan 13 



Circumpolar (arctopolitan) G 



American (exclusively)* 7 



Europseo-Asiatic (or exclusively Old World) t 7 



In regard to the southern extension of these thirty- three -families, thir- 

 teen range far into, and most of them over, the greater part of Intertropical 

 America, and eighteen far into, and most of them over, the greater part 

 of the intertropical portion of the Old World. 



In Intertropical America, only thirty families are represented. Of 

 these, thirteen occur over much of Temperate North America, while 

 eleven are subcosmopolitan, and the same number are peculiar to the 

 region, while one-half of the whole do not range much beyond the 

 northern tropic. Seven are semitropicopolitan, or occur also in the 

 warmer parts of the Old World ; but of these, three are Chiroptera and 

 another is marine. The approximate range of the families represented 

 in Intertropical America is indicated in the annexed table. 



"Five only are exclusively North American, 

 t Two only are exclusively " Palaearctic ". 



