EXERCISE XII 

 ZOOGEOGRAPHY 



The laboratory exercises in Zoogeography will be limited to the condi- 

 tions in North America. Their object is to develop a general knowledge 

 of the environmental conditions in North America, and their relations to 

 the ranges of animals. Vertebrates are principally used because the ranges 

 are better known. The maps should be carefully and neatly prepared as 

 otherwise their significance will be obscured. 



A. GENERAL AREAS OF ENVIRONMENTAL CONDITIONS 

 IN NORTH AMERICA 



North America may be divided into several regions which have 

 characteristic physical conditions. These areas support characteristic 

 floras which provide an easy means of establishing their boundaries. 

 It should be kept in mind that the boundaries of the different regions 

 are sharply drawn only at the seashore; where the regions come together 

 inland there is in every case a zone of transition due to the fact that the 

 environmental conditions change gradually and not suddenly. 



1. On an outline map of North America indicate by shading or 

 symbols the location of the areas covered by the following floras : conif- 

 erous forests, deciduous forests, prairies, plains and deserts. The map 

 in " Principles of Animal Biology" (Shull, LaRue and Ruthven), Chapter 

 XIV, may be followed in preparing this map. 



2. Compare the map just made with the map of the regions in eastern 

 United States given in " Principles of Animal Biology" and note the sub- 

 regions into which general regions may be divided. Note the transition 

 areas. 



B. DISTRIBUTION OF SOME TYPICAL ANIMALS 

 OF NORTH AMERICA 



3. Plot upon outline maps of North America the ranges of several 

 exclusively terrestrial animals. Any of the following forms are suitable. 



3a. Two of the garter snakes, Thamnophis radix and Thamnophis 

 butleri. Their ranges 1 are described by Ruthven, Bull. U. S. Nat. Museum, 

 No. 61. Plot the ranges of both species on one map. 



1 The maps from these books may be duplicated and furnished to the students in 

 sufficient numbers. 



67 



