KELLOGG: TAXONOMIC VALUE OF SCALES OF LEPIDOPTERA. 57 



of moths whose flight-function is not so excessively cephalized. 

 Which, indeed, is to be expected, because of the lesser importance 

 of the hind wings in cases of extreme cephalization of flight. 



This is well shown within the limits of a single family in the case 

 of Calyasymbolas tnyops, a Sphingid with the hind wings large in 

 comparison with the hind wings of CJicerocampa, Philampelus, Ellema 

 and others showing extreme cephalization of flight. In Calyasymbolas 

 the disk of the hind wing is uniformly covered with flat scales, only 

 the basal third of the wing showing long, weak scale-hairs. In 

 Phila7npelus achemon only the marginal brown edging is composed of 

 specialized scales, without thepresence of scale-hairs, while all the discal 

 and basal portion of the wing is covered with long, rather thickened 

 scale-hairs, in addition to flat scales. Ch(2rocavipa tcrsa shows a 

 similar condition, as also does Ellema bombycoides. 



The fact that a heavy flyer shows a less specialized scale-covering 

 than a swift flyer is also illustrated among the Sphingidae. Triptogon 

 modesta, a slow, heavy-bodied moth compared with Philampelus, has 

 its forewings covered with long, thickened, two- to three-pointed, 

 rather flattened scale-hairs thickly inserted, but rather assurgent, and 

 not closely appressed to the wing-surface. The hindwings bear 

 elongate, single-pointed scale-hairs, and also some scales like those of 

 the forewing; altogether a much more generalized condition of 

 scale development than that of Philampelus, whose forewings are 

 uniformly covered with broad three- to seven-pointed flat scales, 

 becoming a little longer toward the base of the wing. 



These generalizations are based on an examination and comparison 

 of a large number of forms, and specific examples will be adduced in 

 different groups of moths. 



These conclusions as to what is the most highly specializ d condi- 

 tion of scale and arrangement are further confirmed by the fact that 

 these conditions obtain in those forms of Lepidoptera which are 

 considered by entomologists to be the most specialized forms of the 

 order; a conclusion reached without reference to the scales. The 

 Nymphalidae show as highly specialized a scale-covering as is to be 

 found among the Lepidoptera. It is also true that among those 

 groups of moths considered by entomologists to be the most general- 

 ized, as the Megalopygidce, the scale covering does not attain nearly 

 as specialized a state as among the groups of more specialized Lepi- 

 doptera. 



The most generalized form of the scale apparent on the wings of 

 Lepidoptera is, it is evident from the foregoing, that long, slender, 

 flexible form, between which and the most specialized form, the flat 

 scale, a whole series of gradations, each succeeding form better 

 adapted for its function, is to be found. 



