120 RHOPALOCERA. 
M. montezuma) is slight, and not sufficiently constant to justify the maintenance of the 
two species as distinct. In general, too, the wings of the northern specimens are more 
rounded and the secondaries less pointed than in southern examples. In default of other 
trustworthy characters we therefore unite these two under Kollar’s name, Messrs. Butler 
and Druce having already used it for Costa-Rica specimens?. Its range, from Southern 
Mexico to Colombia, seems quite continuous; and specimens fairly typical are not 
wanting wherever it occurs. With these, however, are mingled others whose position 
is yet open to question. These occur, for the most part, in the State of Panama; and 
we find at Calobre, mixed with a dark-blue insect with a wide black border (agreeing 
with the usual Mexican and Guatemalan form), others of a paler more silvery blue, 
which show distinct spots and lunules on the dark marginal band and an inner row 
of white spots on the primaries. One specimen from the same locality diverges much 
more even than these, in being very pale with the blue much as in UW. octavia, to 
which the insect bears a close resemblance. Were it not that the base of the wings 
in all these specimens is blue, we should class them with M. marinita rather than with 
M. peleides. They undoubtedly form a link between the two. In the form found 
on the line of railway the blue of the wings in both sexes is of a peculiarly dark 
hue, in strong contrast to the light-coloured Calobre Morpho. 
In Guatemala MM. peleides is restricted in its range to the eastern or Atlantic side of 
the main cordillera, where it is common in suitable localities from the sea-level up to 
an elevation of about 3000 feet. In the forests of the Pacific slope its place is entirely 
taken by M. octavia, a closely allied species, but with an unmistakable tint of the blue 
of the wings, which renders it not difficult to recognize. 
With this exception M. peleides is the only Morpho of this form in Guatemala, and 
is fairly constant in its characters in that country. Dr. Boisduval 4 ® considered that 
two species inhabited the northern parts of Central America and Mexico, which he calls 
M. corydon and M. montezuma—a view that, in our opinion, cannot be supported. 
The relationship of UW. peleides with M. marinita is curious; and we believe it 
quite possible to arrange a series of Costa-Rica specimens which would lead from 
M. peleides to M. marinita—M. hydorina, Butl., and M. limpida, Butl., being 
intermediate steps. 
The following theory suggests itself as a possible explanation of this state of things :— 
Before the complete formation of the Central-American isthmus, and when, as was most 
probably the case, islands existed where Costa Rica and the State of Panama now stand, 
and just prior to their union, a Morpho inhabited Costa Rica like If. marinita, and 
another Colombia like J. peleides, none at that time being found in Guatemala or 
Mexico. When the union of the land took place, I/. peleides was the one to spread, 
and pushed its way along the isthmus, passed W/. marinita in Costa Rica, and then 
occupied the rest of Central America, Yucatan, and Southern Mexico. For some cause 
or other, those which established themselves in the Pacific coast-region of Guatemala 
