1964 ] 
Carpenter — Dictyoptilus 
ill 
known at the present time, therefore, the hind wing was of the same 
length or nearly the same length as the fore wing. The accompanying 
drawing (Plate 13, fig. B) of the hind wing of peromapteroides was 
made from the type specimen in the Museum National in Paris in 
1938 and was verified by checking with the specimen in 1961. The 
costal margin of the hind wing is not actually visible in the fossil ; 
the basal part is covered up by the hind margin of the fore wing and 
beyond that point it is broken away; there is, at most, a faint indica- 
tion of what might be a short piece of the margin just beyond the 
edge of the fore wing. The first vein which is clearly apparent in the 
wing is, therefore, the subcosta, which is preserved as a concave vein. 
Below that, the vein R1 is readily recognizable as a strong convex 
vein; its basal part is not preserved, being covered by the fore wing. 
Rs is very closely preserved as a concave vein but unlike Rs in the fore 
wing, it diverges posteriorly away from R 1 and then turns towards 
Rl; the space between R 1 and Rs is actually wider shortly after the 
origin of Rs than it is further along in the wing. In the part of the 
wing preserved, Rs gives rise, in a pectinate manner, to three concave 
branches, separated by several rows of cellules. Rs in the hind wing, 
therefore, differs from that in the fore wing by its more basal origin 
and earlier branching. The rest of the venation of the hind wing is 
even more different from that of the fore wing. The next vein, 
which is not obviously convex or concave, arises near the base and is 
slightly curved ; it first gives rise to a strong convex vein, and beyond 
that it forks to produce two major branches, each in turn forking; 
this whole system is composed of concave veins. The convex vein I 
am, identifying as MA, since it follows the distinctly concave Rs; the 
concave veins below that would appear to be MP. The next and 
only remaining vein preserved in the wing is a strongly curved, convex 
vein, apparently CuA; this is not preserved to its termination but 
the part that is present is almost semicircular. It is difficult to imagine 
what the distal portion of this hind wing was like ; Rs was apparently 
extensively developed distally, no other main veins remaining. As 
noted above, there is no evidence that the hind wing was markedly 
shorter than the fore; the slight indentation of the hind margin cor- 
responds to the first indentation of the fore wing margin. At any 
rate, it is obvious that the fore and hind wings in Dictyoptilus are 
remarkably different in venation — more so, in fact, than those of any 
other Palaedictyoptera known. The fore and hind wings of even 
those genera (as Dunbaria ) which show differentiation of wing form, 
have a similar venation, except for the number and length of anal 
veins. 
