6 Journal New York Entomological Society. t^'°'- ^^• 



importance of this factor; indeed its bearing upon problems of distri- 

 bution is so evidently weighty that one is apt to question whether lati- 

 tude has any influence except as it affects environment. In the case 

 of dorsalis, itself a marked example of an insect clinging to one en- 

 vironment, I have already shown that while the beach sands are neces- 

 sary to the creature's existence, and finding such sands along the 

 coast from the Gulf of Mexico to Massachusetts, it has extended its 

 range that far north, crossing four zonal boundaries in its northward 

 journey, yet it has not preserved an unchanged identity in so doing 

 but passes through the variations called saulcyi, media and scmipicta. 

 Conceding the great importance of environment, I must still maintain 

 that like the factors previously considered it is only one of many 

 affecting distribution. 



In this connection I should point out the various observations of 

 many collectors on the soil and other characteristics of the localities 

 in which the different species occur. Locally it is well known that 

 dorsalis lives on the sea beach, hirticoUis and lepida on the looser 

 sands back of the beach, the latter also on loose white sand inland, 

 marginata on mud flats, all more or less maritime; while an entirely 

 different set of species inhabit the sandy pine barren plains, riigifrons, 

 modesta, consentanca, etc. ; it is also known that while a species like 

 repanda may be found in a variety of semi-moist situations, i2-giittata 

 can be expected only on the still more moist soil adjoining water and 

 purpurea and sexgntfata only on grassy hills or the latter in deciduous 

 forests, at least locally. Each species in short seems to require a 

 special environment and to insist upon it with a rigor that is in 

 inverse proportion to its abundance. 



Moisture. — In dealing with the distribution of the tiger beetles of 

 our western states a special emphasis would have to be laid upon the 

 influence of moisture; indeed in Dr. Leconte's division of the country 

 into districts one is based upon the difference between the dry plains 

 lying east of the Rocky Mountains and the more fertile country bor- 

 dering the Mississippi River. Also in the same connection, the fauna 

 of the saline lakes would require special consideration; but in the 

 eastern parts of the United States, these matters do not present 

 sufficient diversity to constitute important factors. 



Behavior. — The meaning of these peculiarities has been traced 

 back to the larval history of several species by Norman Criddle in 



