Sy 
=) 
op) 
A. T. EVANS 
Fig. 1 Dorsal view of frontal appendage and top of head of Thamnocephalus 
platyurus; A, trunk of the frontal appendage; B, main branch of the trunk; 
(, upper portion of the main branch with its mesial sub-branches; D, inner spur 
of the main trunk; #, Prinicpal branch of the main trunk; this branch is directed 
mesio-dorsally, and with the corresponding branch from the opposite side, forms 
the dorsal arched portion of the appendage; F’, forked tips of the mesial branches 
of the outer portion of the main branch; G, first antenna; H, eye. 
being more or less coiled and the main trunk closed up much like 
the blade of a jack-knife. The appendage is covered with a 
thin, flexible layer of chitin resembling a transparent membrane. 
The tip of each little branch bears a claw-like structure, formed 
by the rather sudden narrowing of the internal tissues, this nar- 
rowed portion tapering to a rather sharp point, the chitinous 
covering following its contour closely. The whole appendage is 
more or less roughened by numerous, small, conical projections 
over its surface. Examination of a number of the smaller and 
probably immature males showed that the number of branches 
of the principal branches varied greatly, but they are quite 
constant in the larger specimens, which would seem to indicate 
