4451 
down to minute details agrees with that of Tetanocera (Dictya) um- 
brarum and consists in both of a considerable number of light 
spots on a dark ground, strictly keeping within the limits of 
the nervures, but often corresponding and fusing in adjoining cells | 
we become convinced that the lighter areas of Cleitamia exactly 
correspond in arrangement and size to marginal light spots of 
Tephritis. The single assumption we have to make is, that along the 
distal part of the front margin six of these spots have coalesced, 
and morover have become separated from that margin by a narrow 
rim of dark pigment, at the same time that a number of spots, 
especially at the proximal part of the front margin, form connec- 
tions with more centrally placed ones and so constitute transverse 
light bars, which extend over the radial nervure. The number of 
these spots is not absolutely constant, though showing a certain 
regularity, as becomes evident by the comparison of the wings of 
Trypeta cribrata with those of Tetanocera umbrarum, showing that 
spots, which in the latter have coalesced, still remain independent 
in the former, T. cribrata therefore probably representing a still 
more primitive State. 
As in the case of the species of the genus Haematopota, here 
also it is possible to arrange a number of nearly related forms in 
a series, showing a regular transition from the primitive condition; 
numerous similar light spots in rows on both sides of the nervures, 
and in certain cells also along the median axis of the internervural 
space, larger light patches occurring along the wing-margins leg. 
Trypeta cribrata] — then continuing through forms like Tetanocera 
umbrarum and Tephritis pantherina, in which the number of the 
spots is diminished, in consequence both of coalescence and of 
obliteration by pigment-ingression (obscuration) — until we cul- 
minate in a form like Cleitamia astrolabei, with its large but less 
numerous light areas, which differ considerably amongst each other, 
and do not seem to respect the limits of the nervures. 
In the opposite direction Tetanocera umbrarum may be compared 
in detail (e. g. the number of the spots) with Tetanocera vittigera, 
on the simple assumption, that the light areas of the former have 
enlarged to such an extent, that they have coalesced in the middle 
of the cells and in so doing have eut up the dark background into 
fragments which in their turn now give the impression of spots. 
Traces of the original extension of that dark background may still 
be seen in cell R,—M, and M,—Cu, in the form of faint dark 
middle-bars. 
But besides Cleitamia astrolabei a number of other species of the 
