8 STRUCTURE OF THE LEPIDOPTERA 



insect studies, we shall have to become acquainted with detailed 

 descriptions given as aids to the identification of species. Now, 

 such descriptions cannot be satisfactory, either to the one who 

 gives or to him who receives, unless expressed in such definite 

 terms as render a misunderstanding impossible. A botanist cannot 

 give an accurate and concise description of a flower without the use 

 of certain names and expressions which have gradually become an 

 almost necessary part of his vocabulary ; neither can an entomo- 

 logist give a really useful, and, at the same time, a succinct 

 description of an insect unless he is acquainted with the names of its 

 parts. Therefore, seeing that we distinguish the various species of 

 butterflies and moths mainly by the arrangement and colour of the 

 markings of their wings, it is really necessary that we should know 

 the names of the different parts of these oi'gans. For this reason I 

 have inserted drawings of a fore and of a hind wing of a butterflj-, 

 together with the names of the various parts of the wings, and also 

 the names of the principal rays or nervures. Yet I would not 

 advise any young entomologist to attempt to commit to memory 

 all the names given. Eather iise the diagram for reference when 

 occasion requires, more particularly when you have an insect in 

 your possession that you desire to study. In ordinary descriptions 

 of butterflies and moths the names of the nervures are not so 

 generally used as those of the parts of the wing. Consequently it 

 is exceedingly useful to know what is meant by the terms base, 

 costal margin, apex, hind margin, anal angle, inner margin, 

 discoidal cell &c. as applied to the wing. 



The two pairs of wings are attached to the second and third 

 segments of the thorax ; but of the three pairs of legs, which we 

 have next to consider, one pair arises from each of the three 

 segments. The arrangement of these limbs is well shown in the 

 sketch on page 3, as are also the names of the different i^arts of 

 the limb, the latter being given for reference by the reader when 

 the need arises. 



All insects, in their perfect state, we are told, have three pairs 

 of legs ; but if you examine the under surface of certain butterflies, 

 such as the Marbled "White, or any of the Vanessas, Browns, or 

 Heatlis, it is quite likely that you will raise objection to such a 

 statement ; for in these you may possibly see only four legs. But this 

 is the result of a too cursory observation. Look a little moi'e closely 

 at your specimen, and you will sec a i)air of smaller legs folded 

 up under the fore part of the thorax. By meims of a blunt needle 



