i;g 



ANNALS NEW YORK ACADEMY OF SCIENCES 



uniform climates are seen in the early Carboniferous, in the Jurassic, 

 mid-Cretaceous and Eocene. Now the base-leveling and overflow con- 

 ditions are obviously favorable to the expansion and groT\i:h of marine 

 life, especially of the littoral and shallow seas. The conditions of com- 

 plete emergence of the continents and restriction of the littoral life to 

 the steep and narrow border of the continental shelf will be unfavorable 

 and will tend to what Chamberlin calls restrictive evolntion of faunas. 



Fig. 2. — The southern continents, south polar projection 



Ocean depths of 100-1000, 1000-2000, and over 2000 fathoms indicated by progressive 

 shading. Less than 100 fathoms unshaded. The sicep margins of the continental shelf 

 are indicated by hachures. The isolation of the southern continents is in contrast to 

 the unity of the northern hind areas. 



Conversely on land, the great emergence of the continents will tend to 

 expansional evolution and cosmopolitan faunas, while their partial over- 

 flow and isolation will tend to the restriction of land migration and the 

 development of provincial faunae. 



EFFECTS OF ALTEIINATIONS OF ELEVATION AND CLIMATE UPON EVOLUTION 



OF TERRESTRIAL FAUNAS 



Associated with the isolated continents, we have moist tropical uni- 

 form conditions of climate, and to this the provincial land fauna? of 



