10 



V. E. SHELFORD. 



clay banks. 1 The range of the adults is far wider. To determine 

 the cause of this distribution, adults were placed in cages contain- 

 ing soil of several kinds. Each kind was so arranged into steep 

 and level parts that about one square foot of each type was ex- 

 posed. The adults placed in the cages were taken when the 

 species was copulating freely. 



The following table shows the number of larvae which appeared 

 in the case of three lots of C. purpurea limbalis. 



Other pairs taken in coitus were placed in cages containing 

 sand only and level clay only. No larvae appeared in either case. 

 Females placed in cages containing rough steep clay, deposited 

 eggs. Similar experiments have been carried out on several 

 other species and it becomes apparent, therefrom, that the local 

 distribution is determined by the egg-laying instincts. Since the 

 animals cannot and do not continuously remain far from the 

 breeding place, the breeding place becomes the true index of 

 their habitat. Their local distribution being determined by egg- 

 laying instincts, in other words by the life needs, and housekeep- 

 ing habits of the animals, it may be called " ecological distribu- 

 tion " from Haeckel's 2 definition of that term, and the etymology 

 of the word. 



Habitat selection in correlation with geological factors such as 

 erosion and deposition, and with the succession of plant forma- 

 tions and societies forms one of the great factors of dispersal, iso- 

 lation, etc. 



^he nomenclature used in this paper is to be found in Horn's " Systematischer 

 Index der Cicindeliden," Deut. Ent. Zeit., Feb., 1905, Supplement. C. scutcllaris 

 Say, however, stands in that publication as obscura Say aber. Lecontei Hald., the 

 corresponding change having been made by the same author in a later publication. 



2 Ecology is the science of the domestic side of organic life, of the life needs of or- 

 ganisms and their relation to other organisms with which they live. " Wonders of 

 Life," 1905. 



