THE YOUNG NATURALIST. 



gical stratum, and consequently presents a great diversity of physical 

 features. 



With a view of obviating some of the foregoing difficulties, a plan 

 was suggested a few } 7 ears since whereby the country was divided into 

 districts, with a river or stream for their centre, or what is termed the 

 " catchment basin " system. At first sight this may seem to be a good 

 and natural division, but on a closer examination, I fail to see that 

 the student would derive much assistance from the scheme, or that it 

 would be of advantage in investigating the fauna of any district ; the 

 tracts of country indicated being often of such vast extent (as in the 

 case of the Thames), and in others too narrow (as in small streams), 

 that nothing particular is pointed out, and, therefore, the divisions 

 serve no purpose whatever. Every student of entomology and 

 botany knows that the characteristics of a district are its most im- 

 portant guides to the species to be found within its borders ; and if he 

 be directed to search particular basins, without a knowledge of their 

 fauna, he would probably commence operation at their centres, where, 

 in most instances, the soil would be nearly always the same, viz., 

 valley-alluvium, consequently similar insects would occur in each basin. 



Districts which possess a variety of soil are of most interest to 

 entomologists ; and this variety is more likely to be found on the 

 ridges of land which form the watersheds than in the valleys, as the 

 underlying strata crop out as we get further away from the river. 

 Thus, if the boundary of a district be made where the water divides, 

 the line must be drawn through the middle of a chalky soil or of a 

 sandy tract, and insects will then be recorded in two or three divisions 

 instead of one : the actual locality being on the boundary of each. 

 In the Thames valley, where the formation varies from the carboni- 

 ferous to the latest alluvial deposit, the indication that an insect 

 occurred there would be quite as definite if it were given as England. 

 Information of this kind is therefore of no practical value to the 

 student, and it would be better, under the circumstances, to leave him 

 to his own resources. 



The time of occurrence, if it be carefully given from actual experi- 

 ence, and not taken from the capture or reputed capture of an insect ss 

 recorded years ago, is often of great assistance in searching for species 

 that are not only difficult to rear, but which also have a very limited 

 period of existence in the perfect state. 



The work of Canon Fowler (now issuing from the press), entitled 

 " The Coleoptera of the British Islands," approaches more nearly to 

 the wants of the student than any book yet published ; it contains not 



