41 
though there has been no appreciable reduction or other modi- 
fication of the fore tarsi, as is so often found in fossorial Lamel- 
licornia. The males show the usual Lucanid tendency to vary 
as regards the mandibles, the head, and prothorax; and the 
species as a whole, the tendency of lignivorous insects in gen- 
eral to vary greatly as to size. The largest males are fully 
21 mm. in length from clypeus to apex of elytra and 11 mm. 
in greatest breadth, while the smallest specimen seen is hardly 
12 mm. in length and 6 mm. in breadth. 
The structures which I have found to be the most impor- 
tant from the standpoint of variability and useful as indices 
for my work, are the mandibles, the clypeus, the submentum 
(the mentum of earlier authors), the sides of the head, the 
fore tibia, and the scutellum, and to a lesser degree the middle 
and hind tibia. In no two specimens from the large number 
under observation, could I find all of the characters abso- 
lutely the same, though in the majority a certain proportion 
of the characters were alike. As regards the mandibles, there 
were found four main types: the first, the generalized and 
usual form with a moderately developed and acute tooth at 
about the middle, such as is shown in Plate I, fig. 1; second, 
a form with the tooth much more elongated and blunt at the 
tip and also projecting somewhat upwards as well as inwards, 
fig. 4; third, a form with greatly elongated, almost straight, 
and toothless mandibles, fig. 5; and fourth, a much reduced 
simple type of mandible with at most only a slight enlarge- 
ment where the tooth should be, fig. 2. The first three forms 
are only found in the males and the last is restricted to the 
females. The clypeus shows that it may vary in three distinc- 
tive ways: have a transverse anterior margin, fig. 1; a pro- 
nounced bi-emarginate anterior margin, fig. 3; or be somewhat 
triangular with the middle much produced, fig. 5. The sides 
of the head are almost straight and parallel in a few, with 
the canthus not prominent and not impinging upon the anterior 
portion of the eye, fig. 3; somewhat rounded and with a well 
developed, more or less tuberculous canthus that decidedly 
overlaps the anterior margin of the eye, fig. 1; and quite 
oblique and converging anteriorly, with but a moderate de- 
velopment of the canthus, though with the same slightly im- 
