( lis ) 

 aucl Cressoina, PI. LXI. 1". 3. 4. b), the (iiiestioii assiuues a ditfereiit asjject. 

 FollowiDg the same line of argument, we slionld luive to attribute to the 

 ancestor of Ceridia an antenna with long pectinations of the first type in both 

 sexes, and to the ancestor of Cressoina one with long pectinations of the second 

 type. Therefore, according to this, the common ancestor of both genera, or the 

 ancestor of the subfamily Amhididnae, would have had an antenna combining 

 both types of pectination — namely, a long subdiirs;il l)ranch and two long 

 subventral branches on each side, a type which does not occur anywhere. If 

 we go further and construe by a similar line of argument the ancestral type of 

 antenna of Sataniiidae and Notodontidae, and then that of the common ancestor 

 of these femilies and the Sfjlniigidac, we arrive at a form of antenna combining 

 all the various types of pectination which are morphogenetically different. In 

 short, if the above line of argument were correct, we should have to attribute 

 to the ancestral antenna of the Lepidoptera all those special features found in 

 the Order which are not derivations from one another. That would be absurd. 

 And yet, if we look over the literature bearing on classification, we often 

 encounter absurdities akin to the above. 



Going back to the alternative presented above, we hope to have now 

 shown that the pectinated antenna is indeed a derivation from the fasciculated 

 one ; that the pectinated antennae of the males are more advanced than the 

 simj)le or the less strongly pectinated antennae of the females, these coming 

 nearer the ancestral form. 



As said above, the specialisation of the male antenna is often observed in 

 the female — the groove, the fasciculated ciliae, and the pectination being more 

 or less distinct. We shall call such female antennae andromorphic in tiie body 

 of this Revision. There are female antennae which are much more strongly 

 compressed and deeper-grooved, and liave longer fasciculated ciliae than the 

 male antennae of other species (compare the genus Foh/ptijchns). 



The sexual differences observed in the antennae of Spliimjidae and other 

 Heterocera are either such of degree, where the male characters reappear in 

 the female, or of kind, where the sjiecial male characters are quite absent from 

 the female ; and the occurrence of such sexual dimorphism is an indication of 

 differences iu function, and not of different capacity in the sexes of acquiring 

 the sjjecialisations. In other organs the females are not rarely more advanced 

 than tlie males ; there is therefore no general rule in this respect. However, 

 it is true of the antennae that the female sex is never in advance of the male. 

 This is cx])lained liy the different role the sexes play in courtship, especially in 

 finding one another, the male antenna being very specialised in cases where this 

 sex lias to search for the sedentary female. The sluggish Ambulicinae have, 

 in accordance with this explanation, on the whole more strongly compressed, 

 grooved, and ciliated antennae, and more often subpectinate ones than the 

 members of the other subfamilies of Spliimjidae. 



Specialisations of one sex are latent in the other, and may occasionally put 

 in an appearance where they are normally absent. For instance, the metallic 



