ANTENNA OF LEPIDOPTERA, 21 



that all siK'h cases of sexual ineciuality liave been gradually reached 

 by a degeneration of one sex attended l)y a corresponding develop- 

 ment of the other, and that a tendency towards such an action arose 

 whenever the females were less active than the males. His chief 

 argument for this theory is that the antennal cases of the pupae are 

 practically alike in both sexes and are larger and more complex than 

 the adult antennte of the female would warrant, though at the same 

 time less developed than the adult male antennae. A different ex- 

 planation, however, may be offered. In these families ovij)osition 

 takes place very soon after the emergence of the female from the 

 cocoon and neither the male nor female adults seek footl to j)rolong 

 their existence. Their m()uth-[)arts have been lost or have ceased to 

 he functional. If this habit of early oviposition was acquired before 

 the antennae had time to develop very far, it is plain that there would 

 lie little tendency in either male or female to attain better antennae 

 for aitl in the search for food. At the same time the struggle of the 

 males to find the females quickly would cause a sudden and extreme 

 specialization of their antennae, without a corresponding influence 

 upon the female. Darwin has pointed out that " peculiarities ap- 

 pearing in the males of our domestic breeds are often transmitted 

 either exclusively, or in a much greater degree in the males alone." 

 This would seem the more natural explanation of the condition we 

 find among the Lepidoptera. It is so common to find the female 

 with antennie much less developed, that it is difficult to believe that 

 they all have degenerated from a form intermediate between the 

 l)resent male and female antennae. It is a much simpler and reason- 

 able explanation and one which is as fully in accord with the facts 

 to believe that in the large majority of cases the females have simply 

 not kej)t })ace with the males in the specialization of their autennie. 



Whichever may be the true explanation, the comparative study 

 of the series is equally instructive. Degeneration is apt to retrace 

 the steps by which the form Avas specialized, and so affords nearly as 

 good illustrations of intermediate stages as would the real progressive 

 series. 



Another suggestive serie-s is afforded by the gradation of the pec- 

 tinations on the different portions of the same antenna. The medial 

 and proximal parts show the more advanced stages, while the distal 

 retains the earlier and simpler ones; see the gradation in Fcltia 

 subgothica, Figs, 9, 11, 10. This, however, is not true in the case 

 of those organs which find their most favorable situation at the 

 distal end. 



TRANS. AM. ENT. SOC. XXIII. JANUARY, 1896. 



