ON SPECIES ANn VARIETIES. 351 



of Cnritbida : these, therefore, must be examined with 

 more attention. The size of the bill, and the relative 

 length of the quill-feathers, among birds, will often, in 

 the absence of other information, decide the question. 

 The pattern, form, &c. of the rows of punctures in the 

 wing-covers of beetles is also a good criterion. A smooth 

 and a hairy beetle can never be of the same species. 

 The young entomologist will do well to collect together 

 all the specimens he meets with, in his walks, of the 

 Linnaean genus Carnhus, and then sit down, and endea- 

 vour to make out how the different sorts of all those 

 which may be of a black colour can be distinguished. This 

 plan will greatly awaken his powers of observation ; 

 and he will then be surprised to find how many of those 

 he first thought were tlie same, are really different. 

 The species, in some genera, much more closely resemble 

 each other than in others. Thus, among shells, the 

 different tellens ( Tellince) are only to be known by nice 

 distinctions in their form and sculpture, that is, the 

 indented or elevated marks or strife upon their valves. 

 These shells are further remarkable for the great variety 

 they exhibit in their colours : for, of the same species, 

 it will sometimes happen that scarcely two individuals 

 will be of the same tint. Colour, moreover, is a most 

 uncertain guide for distinguishing the pectens. Our 

 common English species varies between every shade of 

 dark brown, rich orange, pink, and pure white. The 

 form and sculpture, however, in all these varieties, are 

 the same ; but the most difficult of all shells to cha- 

 racterise are those of the oyster family, where even the 

 shape varies in different individuals. Lepidopterous 

 insects are best distinguished by their markings, as the 

 form, number, and relative disposition of their bands 

 and spots, both on the upper and under surface of their 

 wings. Sometimes the upper surface of the greater 

 number (as in the SatyridcB) will be uniform brown ; 

 while in other groups, as the genera Thecla and Polyom- 

 matiis, the prevalent colour will be blue. In all these, 

 however, the under sides are variegated in a beautiful 



