ON SPECIES AND VARIETIES. 351 
of Carabide: 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 
Linnean genus Carabus, 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 the same, are really different. 
The species, in some genera, much more closely resemble 
each other than in others. Thus, among shells, the 
different tellens (Telling) are only to be known by nice 
distinctions in their form and sculpture, that is, the 
indented or elevated marks or stri@ 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 Satyride) will be uniform brown ; 
while in other groups, as the genera T'hecla and Polyom- 
matus, the prevalent colour will be blue. In all these, 
however, the under sides are variegated in a beautiful 
