DR. F. LEUTHNER ON THE ODONTOLABINI. 415 
My prolonged morphological studies have led me to the conclusion that the 
remarkable species 0. gazella, Fabr., is nearly related to the above species, notwith- 
standing its great apparent differences. In 0. gazella the mandibles are always 
monstrously developed both in large and small males for some reason which cannot 
yet be even guessed at (Pl. XOVI. fig. 10). The large head, the broad prothorax, 
the long incurved front tibize channelled in front, and the strongly developed prosternal 
process make it probable that this species is derived from one in which the mandibles 
were normally developed as in other species, and afterwards, during the insect’s com- 
petition with other species, developed into these extraordinary pincers. . This view is 
supported by a unique specimen in Herr van Lansberge’s collection, in which the 
mandibles are bilaterally and symmetrically developed, and have an inner branch in 
the middle (Pl. XCVI. fig. 104). The great pugnacity of this insect is manifested by 
the many wounds which it has received in conflict with other males. The canthus is 
bitten away, the central tooth of the right mandible is broken off, and there is an 
indentation at the tip. These injuries have certainly been caused by the mandibles of 
another individual, as the shape and character of the injuries clearly indicate. The 
necessity for defensive organs may have resulted in the widening of the canthus in 
both sexes. I have been led to this conclusion by the following considerations :— 
(1) The geographical distribution corresponds to that of the last-mentioned species. (2) 
Similarity of the females. (3) Resemblance of the amphiodont forms of 0. wollastoni 
and O. ludekingi (Pl. XCIII. figs. 9, 11) in the shape of the head and in the structure 
of the mandibles. (4) In all these species the rim of the elytra is black on the under- 
surface. (5) The front margin of the prothorax in O. Jacordairii (Pl. XCIV. fig. 2) 
has a tendency to become narrowed in front. (6) In all the small forms the legs are 
curved, and the front tibie are channelled. (7) The canthus, if we imagine the 
excavation to be filled up, would agree in all these species. Finally (8), agreement in 
the form and size of the prosternal process. 
The characters of 0. gazella being once permanently fixed, it becomes easy to under- 
stand how this species may have given rise to insular races, which were but slightly 
modified at first ; and how a geographical subspecies, 0. inwqualis, Kaup, distinguished 
by the uniform dark colour of the elytra, might become differentiated in the island 
of Nias (Pl. XCVI. fig. 12). In this form the mandibles (fig. 12 a, 6) remain apparently 
unaltered, but the number of spines on the front tibie is reduced. Unfortunately 
the female of znequalis is still unknown, and we do not know whether its coloration 
has become modified like that of the male. 
(v.) Group of O. castelnaudi. 
Although this group appears at first sight to contain very dissimilar species, a 
thorough examination shows them to be more closely related to one another than their 
external appearance, and sometimes variable coloration, might lead us to expect. In 
