420 DR. T. A. CHAPMAN ON THE SPECIES [Apr. 27, 
priority. Such new practice, moreover, would only be binding 
after each case was determined by a Committee, appointed by the 
Zoological Societies of the world. Short of this it would only 
prolong the confusion due to a struggle ultimately to be decided 
in favour of priority. 
I was led to examine this group by Mr. Tutt desiring me to 
investigate Z. argiolus. I found this could not be done “without 
dealing with a number of other, chiefly Indian, species, and these 
again required, or at least suggested, a still wider view, so that I 
finally took up the whole genus, so far as I could obtain access 
to material. No doubt, my view is still narrower than it ought 
to be, because I have not gone fully into the most nearly allied 
genera. I have, in fact, made observations of some of these, 
but it was obvious that I must draw the line somewhere and take 
the risk of such errors as ignorance of what was beyond it might 
lead me into. 
Another serious limitation was found in the fact that specimens 
of some species could not be obtained for examination, and this 
unfortunately was apt to affect most especially type and other 
more valuable specimens. Still, I have examined a great deal 
of material, but there are six species of which I know little, of one 
of these only the 2 is known, and several of the others seem to 
be probably synonyms. 
I have examined a. good many species in the British Museum 
Collection at South Kensington, and am also under great obligation 
for the privilege of examining many specimens from the Rothschild 
Collection at Tring. Mr. H. H. Druce has afforded me assistance 
with specimens and aid in determining species. Mr. Bethune- 
Baker has kindly allowed me to examine specimens including 
several types from his collection, JI have also had specimens 
from the Godman Collection, from that of the Oxford University 
Museum, and elsewhere. The late Col: Bingham also most 
kindly assisted me with specimens and afforded me the valuable 
aid of the researches he had made in writing the volumes on the 
‘“‘ Butterflies” in the ‘ Fauna of British India.’ 
I have. found considerable difticulty in making sure that the 
specimens I examined were correctly named, and in the absence 
of access to types of well-known species, the authority of the 
works of Moore, de Nicéville, and Bingham, for the Indian species, 
was generally found to be adequate. 
My observations of the genus lead me to the conclusion that 
the upper surface is often more misleading than otherwise as to 
what species some particular specimen belongs to. As to the 
under surface, I believe the pattern of the spotting is to be 
thoroughly depended on for specific characters. But then it 
unfortunately happens that the pattern is not unfrequently quite 
obscured by seasonal, geographical, and other variations, the spots 
being much enlar, zed, or some of them reduced almost or quite to 
obsolescence. They may be very dark or very pale, and so on. 
It has happened to me several times that I saw no identity 
