60 GROTE—THE DESCENT OF THE PIERIDS. [Jan. 5, 
resentation in tertiary than inrecent time. For the Miocene strata 
of central Europe contain a number of types of vertebrates and land 
shells which are now confined to America, but at that epoch en- 
joyed so wide a distribution. In Europe these types subsequently 
disappeared, giving place to more specialized types, but in America 
they have persisted. Without having seen the specimen I could 
not venture upon an opinion not in accord with that of so reliable 
an observer, and what I now point out is that the wings of the 
Blues and Skippers nearly agree, and I repeat that it is probable 
that the former group has emerged from the same immediate stock 
with the latter. Another circumstance to be noved is that the ter- 
tiary species are generally distinct. This leaves room for the suppo- 
sition that the diurnals have changed both a good deal and compara- 
tively rapidly. It seems that the Nymphalids flourished in the tertiary 
and that the quaternary is evidently the epoch of the Pierids and 
the Blues, so that we may safely regard these latter groups as among 
the more modern types of butterflies. 
With regard to the phylogenetic line A, the Papilionides, we 
know, from Dr. Rebel’s researches, that its most advanced group, 
the Parnassians, existed in the Miocene. Nocertain identification 
of fossil remains of the Swallowtails proper, the Papilionidz, ap- 
pears to have been yet made anywhere. But if my views are cor- 
rect, we may yet discover that Ornithoptera-like forms had a wider 
distribution in preceding epochs than at the present time. The 
classification and the general theory of the development of the diur- 
nals, brought forward in this present and previous communications 
to the American Philosophical Society, is so different from the gen- 
eral opinions and conclusions of other authors, that I have given 
them with diffidence and in all deference. My views have gradually 
shaped themselves out of the discovery of the directions of the 
movements which undoubtedly occur in the evolution of the vein- 
ing of the Lepidopterous wing. While I have tried to correlate 
the subordinate types, I have endeavored to make it quite clear that 
there are two antagonistic and principal types in the neuration of 
the diurnals, and that this fact authorizes the belief that the Papil- 
ionides and Hesperiades may have had an independent origin. 
MImIcry. 
None of my predecessors appear to have studied the phenomena 
of mimicry in connection with the structure and specialization of 
