154 
K. OGUMA. 
This subspecies is easily distinguishable from the type in the following 
points. 
1. Size much smaller. 
2. Head, thorax and 1-2 segments of' tbc abdomen dull bronz, while 
metallic green in the type. 
3. In the male, wings without pearly reflection, not smoked along the 
costa and the apical opaque area highly reduced, only the small part beyond 
pterostigma brownish. In the female, wings faintly smoked and the apical 
opaque area being much smaller. 
The lack of iridescent nature in the wings of males is the most important 
peculiarity to separate this subspecies from the type. It might sometimes 
be taken as a distinct species whenever the details are not sufficiently studied. 
Nom. Jap. Kuroiwa-kawa-tombo. 
Loc. Loo-Chco (Kuroiwa). 
Genus Mnais Selys. 
Three species belonging to the present genus have been known to occur 
in Japan, viz. Mnais strigata, Mnais pruinosa and Mnais costalis. All of 
them were first described by Selys although the first had been authorized 
by Hagey; to Selys, however, the femels 11 of the last two were utterly 
unknown. By comparing the wing color only, these three, if be males, are 
easily distinguishable each other, but whenever we intend to sparate them by 
the females only, then we always find much perplexity thereon. They have, 
in the females, the wings of similar color, so they have a similar appearance 
to the males of 3Inais strigata except the color of pterostigma. The three 
species live always in the same places, at least 31. strigata 31. consialis, in my 
observation, mingling each other along streams, consequently whenever the one 
is found the other can whithout exception be met with. I have occasionally 
caught the couples of both species in copulation, but the attempt to distinguish 
them by females only was in vain. After much consideration I wish now to 
combine them into one species recognizing the polymorphic nature in males 
1) They are preserved in the college-collection in a large lot. 
