522 
Psyche 
[September-December 
The surfaces which are concealed by the shortened forewings, how- 
ever, are relatively free of debris. Except for the third abdominal 
tergite (Fig. 2, T3) these regions appear smooth under the stereo- 
scopic microscope (Fig. 2, light stippling on right side). The smooth 
terga and the inner (ventral) surfaces of the forewings lack fringed 
setae and are covered with densely-packed hydrofuge hairs. Those 
on the metatergum (T III) and second abdominal tergite (T 2), 
which were examined in more detail, possess nodules basally, are at 
least 5 [im long, and have diameters similar to those of the plastral 
hairs on the ventral surface of the body. The hairs on the inner 
surface of the forewing are considerably shorter (approximately 
1.5-2 fim in length) than those on the second abdominal tergite and 
metatergum. Basal nodules were observed on these alar hairs only 
in the region of the forewing which is externally visible in ventral 
view (Fig. 1, FW) ; here the hairs are longer, but since their tips 
appear to coalesce their height could not be estimated. 
The surfaces which are exposed to the water are covered with 
small, wart-like, cuticular protuberances which give them a roughened 
texture. The raised surfaces of these protuberances, which are ap- 
proximately 20-35 fim in diameter and one to two times this distance 
apart, lack hairs. Each “wart” bears a small central indentation con- 
taining a curious fringed papilla, possibly a sensory device. The large 
spaces between the protuberances were, unfortunately, covered with 
debris on all of the exposed abdominal tergites. The anterior third 
of the third abdominal tergite, however, is overlapped by the posterior 
edge of the forewing, which largely protects it from debris. In this 
region, densely-packed hairs, at least 5 fim long and 0.3 to 0.4 /xm 
wide at the tips, cover the areas between the cuticular “warts”. 
Similar hairs occur between the protuberances on the exposed portion 
of the mesothoracic tergum (Fig. 2, T II). Quite probably hydro- 
fuge hairs are present between the protuberances on the prothoracic 
and fourth through seventh abdominal terga, but are hidden beneath 
the debris. Occasional fringed setae occur on all of the exposed dorsal 
surfaces of the body, and are especially numerous along the lateral 
edges of the abdominal terga and in the abdominal intersegmental 
sulci. 
Discussion 
Although in most areas the fringed setae appear to be too widely 
spaced to retain an air layer, at least two of the other three types of 
fine structures on the cuticular surface of Cryphocricos appear to be 
