78 



found in the Noctuidce where they are bristled beneath, scaled above, and about two- 

 thirds the length of the fore wings. 



The thorax supports the organs of locomotion, the legs and wings. The former are- 

 six in number and consist of five joints. They are attached to the thorax by the basal 

 joint or coxa, and there is a small piece, the trochanter, between this and the femur, which 

 is stouter than the following tibia, the leg terminating in jointed toes or tarsi. The tibiae- 

 are often armed with spines or prickles, while the fore pair terminate sometimes in claws 

 at the sides. In addition the middle and hind legs bear a pair of spurs. When the 

 thorax is denuded of its vestiture it is seen to consist of three principal divisions, pro- 

 thorax, mesothorax and metalhorax, of which the middle piece is the largest. The wings 

 are four in number, and are attached usually in the moths by a bristle and hook ; the 

 former is divided in the females and simple in the males, and is situated on the hind 

 wings beneath near the upper edge of the wing ; the bristle fits into a sort of socket on. 

 the under surface of the fore wings near the base. This character is wanting in the but- 

 terflies and in some moths, and seems to be an aid in keeping the wings together when* 

 flying. According to the system originally proposed by Dr. Herrich-Schaeffer, the ribs 

 or nervures of the wing are numbered from one on, commencing on the inner margin of 

 each wing. The marginal nervure is wanting, and the subcostal and median nervures 

 form a median cell and branch out into secondary veinlets thrown on the costa and 

 external margin. An accessory cell is sometimes formed beyond the median cell, but the 

 median cell is often open, and there are, as a rule, no cross veins on the wing. The sub- 

 median vein or nervure is usually simple. The interspaces between the nervures are also 

 indicated in descriptions so that the markings may be more accurately located. The fore 

 wings are, according to this system, 9 to 12 veined, the number depending on the second- 

 ary veins which afford generic characters. The hind wings are similar in structure to the 

 fore wings. They also vary in the number of secondary veins, of which there are usually 

 7 to 8. These veins are in reality hollow rods through which, when the insect escapes 

 from the chrysalis, air and blood are forced by an action of the muscles of the thorax. 

 They finally become dry and rigid. The wings in insects are thus not analogous to the 

 wings of birds ; they are outgrowths of the tracheal system and have only a common 

 function with the wings of vertebrate animals. In order to study the neuration of Lepi- 

 doptera the wing must be denuded of scales. This is most easily accomplished by a pro- 

 cess invented by Mr. George Dimmock by which the coloring matter is removed from the 

 scales. For this process the wing, previously moistened with ether to remove all fatty 

 matter, is placed in a solution of chloride of lime. From this it may be transferred from 

 time to time to a weak solution of acid to hasten the action of the lime water which, in 

 a short time, decolorizes the scales, rendering them entirely transparent and allowing 

 the course of the veins to be exactly made out. Wings prepared in this manner may be 

 transferred to glass slides and mounted for the microscope. 



A study of the wings and external parts of the Lepidoptera leads to the conclusion 

 that the genera are founded on comparative characters. Rarely does the presence of a 

 peculiar structure of some of the organs give a strong character to the genus. The con- 

 clusions, with regard to classification, to which I have arrived are, that the generic char- 

 acter must be dealt with in principle as are those separating the individuals into species. 

 The limits of the genera depend on the want of intermediate forms, the important point 

 being that the combination of characters which constitute the genus shall be readily siz- 

 able by the student and verifiable. Nature seems to be concerned with the individual 

 rather than with our divisions, which are to a certain extent arbitrary and matters of 

 convenience for our better understanding of these organisms. 



Subordinate to structure in the moths are the pattern of ornamentation and color- 

 ation. The former is of the most value in associating species, although the latter is very 

 characteristic in the different groups. In the butterflies we see for instance that the 

 Satyrid<r, or Meadow Browns, are of a dusky gray or blackish brown color, shading to 

 reddish or yellow, while the wings are usually ornamented with eye-like spots. The 

 Pierid(F are usually white, yellow or orange of various shades with black margin to the 



