MOTHS AND BUTTERFLIES. 



473 



as well as three ocelli, or simple eyes. To the thorax, or the portion of the body 

 corresponding to the three anterior segments of the larva, bearing the three pairs of 

 true legs, are now attached the more complicated legs of the mature insect, as well as 

 two pairs of broadly expanded wings, traversed by a network of muscular veins, :md 

 covered by scales of feather-like form, of various sizes and colors. In one group, the 

 Nymphalidae, the fore pair of legs are aborted, while in other groups they are devel- 

 oped to a remarkable extent. The nerves traversing the wing are modelled after one 

 general pattern, though differing in detail, the central portion of each wing being 



FIG. 598. Wings, with discoidal cell opened and closed. 



largely unoccupied by the nervules, and comprising the space known as the discoidal 

 cell. In some families this cell is open in the lower pair of wings, in others it is 

 closed by a cross nerve, thus affording a strong character for the division of the sev- 

 eral groups, which will be hereafter attended to. The abdomen is only moderate in 

 size in the butterflies, and is composed of six or seven segments, for the most part 

 densely clothed with hair. The legs, which, as we have seen, are attached to the 

 thorax, are composed of nine joints or pieces, the coxa, trochanter, femur, tibia, and 

 five-jointed tarsus. There is in the butterflies always a long-pointed spur at the junc- 

 tion of the tibia with the tarsus, and the latter is terminated by two sharp claws. 

 Any extraordinary development of the legs of butterflies tends towards that of length 

 rather than of thickness ; as the creatures do not walk, but fly, and their legs are used 

 chiefly as organs of prehension. 



The first great group, the HESPEEID^E of authors, contains, according to Kirby, 

 fifty-two genera, and about eight hundred species, in which "the six feet are of 

 uniform size in both sexes ; the hind tibias have a pair of spurs at the apex, and gener- 

 ally another pair near the middle of the limb, a character found in none of the preceding 

 butterflies; the hind wings are generally horizontal during repose, and in some species 

 all the wings are placed in this manner. The antenna? are wide apart at the base, 

 and are often terminated in a very strong 

 hook ; the labial palpi have the terminal 

 joint very small ; the spiral tongue, or 

 maxilla3, is very long; and the discoidal 

 cell of the hind wing is not closed." They 

 constitute a primary division among the 

 butterflies, which Boisduval has termed Involuti, from the circumstance of the cater- 

 pillars enclosing themselves in a curled-up leaf; thus, as in many other important 

 particulars, approaching the moths. The chrysalides are mostly smooth or very 

 slightly angular, attached by the tail, as well as girt round the middle, and enclosed 

 in a thin silken cocoon. 



The United States are rich in species, our catalogues containing not less than 



FIG. 599. Hesperian larva. 



