( bai =) 
with it. Dorsal plate 1 is normal; but the dorsal plate 2 is 
split on the right side only into 2 half-plates, narrow where 
the division commences, but dilating to their usual width at 
the side of the insect, so that left dorsal half-plate 2 and right 
dorsal half-plates 2 + 3 form together the second dorsal plate 
of the whole abdomen. The third and fourth dorsal plates, 
consisting respectively of left dorsal half-plate 3 + right 4, 
and left + right 5, show no visible peculiarity. But the fifth 
plate, which (counting down the right side) should be the 
sixth, is armed on that side with the hook which characterizes 
the sixth dorsal plate, while on the left side it is simple. The 
next plate is most peculiar, having on the left side the basal 
hook of a sixth segment, and on the right the lateral apical 
tooth and half the central apical tooth of a seventh: and then 
follows (on the left side only) half of the ordinary tridentate 
apical plate with nothing at all to match it on the other side, 
the right half of the ordinary apex having appeared already 
in the preceding segment. 
It seems very difficult to form any clear idea of a cause 
which could have produced the phenomenon before us. It 
can hardly have anything to do with gynandromorphism, for 
there is nothing suggestive of ? characters about the insect, 
and its genital armature (which is extracted and pinned on a 
