18 GROTE — SPECIALIZATIONS OF LEPIDOPTEROUS WING. [Jau. 21, 



footed butterflies. But, commonly, we can tell a Nymphalid from 

 a Satyrid by this character. Again, on the hind wings, the Nym- 

 phalidae proper show vein ivg entirely joined to the cubitus, and 

 not issued from the cross-vein. In the Limnadidae, Heliconidae 

 and Agapetidae, which appear to form another branch of the 

 "brush-footed" group of butterflies, this latter condition of vein 

 ivg is only reached in a small group of specialized Satyrids, the 

 Pararginae. This character is plainly secondary, one which might 

 occur independently in diff'erent groups not immediately phylo- 

 genetically connected. 



The specializations of the lepidopterous wing, here chiefly 

 considered, are visible among what I have called the "movable 

 veins " and cannot be relied upon as decisive in general phylogeny. 

 Their study leads to an arrangement of genera and species, 

 in most cases upon a more positive basis, by supplying us with a 

 gauge by which we may distinguish the younger from the older 

 form. The norm by which these specializations are apprehended 

 lies in the principle we have already set forth : the amount of the 

 absorption is the measure of the specialization. 



The two principal directions in which the specialization is 

 manifested are: i. the suppression of the media, common to 

 both wings, and 2. the suppression of the branches of the radius, 

 confined to the fore wings in most Lepidoptera and occurring 

 sporadically. The latter is probably reminiscent of that action 

 which has completed its task upon the hind wings of such Lepi- 

 doptera which have the radius already reduced to a single un- 

 branched vein.^ 



Nomenclature. 



The application of literary terms to structural groups, wider in 

 extent than specific, has become uncertain through the publication 

 of varying and subjective opinion. It has, therefore, become neces- 

 sary to associate the generic title with a single specific type, ascer- 

 tained by historical methods, in order to go safely. The failure to 

 employ the name of the genus in this manner renders Mr. Renter's 

 recently published volume at times unintelligible. The same 

 remark applies to Dr. Chapman's admirable paper on butterfly 



1 Consult, " Mittheilungen a. d, Roemer Museum," 8, February, 1897; "The 

 Hind Wings of the Day Butterflies," Can. Ent., 29, 174; also several other 

 papers more recently issued. 



