DIURNAL LEPIDOPTERA. 77 



on that account claims for thorn a high rank. In the larva of Cerura 

 we find a much more extraordinary special developu)ent than the 

 caterpillars of the Swallow-tails can boast; the anal prologs become 

 long, cylindrical tubes, extending backward and upward, from out of 

 which when provoked, the caterpillar thrusts a highly colored and 

 banded fleshy tentacle, with which it lashes its body to frighten away 

 intruders. Yet in other points of its structure it perfectly agrees with 

 its kindred. Then again if we examine the lips of the closed osma- 

 teria of the Swallow-tails, we shall find them of a corneous nature, 

 resembling nO other feature in butterfly larvae than the chitinous 

 dorsal shield on the first segment of the caterpillars of skippers ; we 

 have therefore in the osmateria themselves indications of a low origin, 

 a relationship with the skippers which most other points in the struc- 

 ture of the Swallow-tails exhibit. The recurved club of the antenna 

 recalls most strikingly the structure of the antennal tip of the higher 

 skippers* and are unlike those of any other group of butterflies. The 

 inner border of the hind wing also is folded longitudinally just as it 

 always is in the skippers and rarely in other butterflies ; moreover this 

 fold is utilized in many males for the concealment of peculiar sexual 

 hairs, and thus becomes very similar to the costal fold on the fore 

 wings of many male Hesperides, and quite unlike anything else in 

 other butterflies. ]5ut perhaps the most striking point of affinity be- 

 tween these two groups lies in the possession, on the front tibiixj, of 

 the same characteristic foliate epiphysis, which is wanting in all other 

 butterflies ;f this, like the possession in skippers of two pair of spines 

 on the hind tibiae is certainly a mark of degradation, by which they 

 are allied to the lower families of Lepidoptera. The eggs of the 

 Swallow-tails, so far as known, are subspherical with a flattened base 

 and almost absolutely smooth, in which they are unlike the eggs of 

 any other butterflies excepting those of the Astyci among the skippers 

 (and excepting, perhaps, that of Nemeobius), while those of the Pierids 

 have closer resemblance to the eggs of Hesperides. J We find there- 

 fore that in the very peculiarities of their structure wherein they 

 depart from the higher butterflies, they are most closely related to 

 the skippers. 



But again the Swallow-tails are universally conceded to be so closely 

 allied to the Pierids that they are invariably placed next them ; con- 



* Compare, for example, the autennse of Iphiclides Ajax and Sespcria ruralis. 

 t Cf. Speyer, Oken's Isis, 1843, 166, 



X See my paper on the two principal groups of UrbicoljB. Bull. Buff. Soc. 

 Nat. Sc. I, 195—6. 



TRANS. AMER. ENT. SOC. VI. (11) JUNE, 1877. 



