March, :9i2.] LeNG : CiCINDEI ID^ IN EASTERN NORTH AMERICA. 3 



Within the genus no proposed division has been generally accepted; 

 but it is evident that two groups can be readily distinguished, the one 

 containing the long-legged species in which the subapical margin of 

 the elytra is often more or less emarginate and the mandibles more or 

 less toothed, and the short-legged species in which such modifications 

 of the elytra and mandibles do not occur. Other characters like the 

 long labrum of loiigilabris, the form of the clypeus, and of the thorax, 

 the pilosity and punctuation of the surface serve to separate species, 

 but the important group character seems to me now to lie in the 

 length of the legs. In the box, to which I have already referred, of 

 South American forms you will see some of these long-legged forms 

 which occur also in the \Vest Indies, in Central America, in our 

 Southern States, and represented by a few species even north to 

 Massachusetts and Maine. 



In concluding this brief reference to the different tribes and genera 

 I wish to repeat and emphasize the northward procession of the 

 family with numerous genera in South America, fewer in the Antilles 

 and Central America, four only in the United States, with a corre- 

 sponding procession of the long-legged species of Cicindela, diminish- 

 ing in number northward, until tiiarginata alone remains to represent 

 them on the coast of Maine. 



Factors Controlling Distribution. 

 Mcrriain's Zones. — Many considerations involving the causes of 

 the distribution observed for different species of plants and animals 

 have been advanced and each doubtless has its bearing upon the 

 problem. The work of Merriam in defining certain zones based 

 largely on the isothermal lines has been widely adopted as the exponent 

 of the influence of temperature. In his pamphlet " Life Zones and 

 Crop Zones of the United States " the Atlantic Coast is divided into 

 tropical, gulf-strip, lower austral, upper austral, transition, and boreal. 

 His map shows the meaning of these terms more plainly than any 

 description I could give and you will note how irregular the lines 

 become on leaving the coast, the colder zones descending far south- 

 ward in the mountains, while the warmer zones, shown by yellow 

 color, creep northward along the rivers like the Hudson and the Sus- 

 quehanna. In the box I have prepared, colors corresponding to those 

 shown on Merriam's map have been used to indicate the zones and 



