406 DR. F. LEUTHNER ON THE ODONTOLABINI. 
mandibles step by step from one moult to another, the above conclusion would be 
positively demonstrated. 
I spared no trouble to seek for examples among these insects in which the full-grown 
male possesses enormously developed mandibles like the Lucanide, which are nor- 
mally developed in the female. As Nature works on parallel lines, I found my views 
confirmed in an Australian cricket (Anostostoma australasie, Gray), in which (as shown in 
the accompanying woodcut, fig. 5, p. 405) the sexually-mature male has enormously 
long and strongly curved mandibles (nos. 1,2). There is an apical cluster of teeth, and 
a broad obtuse tooth, used for masticating, at the base (no. 2, side view). 
In the female the mandibles are small, and are set with serrated biting teeth on the 
inner side (like a priodont form, ef. no. 3). The very young larva of the male, the 
sex of which can be recognized at once by the absence of an ovipositor, begins at the 
same stage as the female in the development of the mandibles (no. 4). 
The enormous mandibles of the male are apparently here also designed for grasping 
the female, and have been gradually developed in this manner by the survival of the 
fittest. 
As the Orthoptera continue to take nourishment constantly throughout the whole 
course of their lives until their death, which soon follows coition, a total change 
of function in the mandibles, as in the Lucanide (from the mandibles of the larva 
to the mandibles of the imago), is impossible; and when the mandibles are needed 
to fulfil an additional function, their increase in length necessitates the lengthening 
of the entire buccal apparatus (the labrum, maxilla, &c.). Only in this strange and 
paradoxical manner could the two objects of the mandibles be fulfilled without inter- 
fering with one another. 
(6) Divergence of Species in the Odontolabini. 
(Investigations into the Agreement and Difference of the Morphological Characters, as 
a Contribution to the Knowledge of their Mutual Relations.) 
In the previous Chapter we treated of the variations which occur within the narrow 
limits of a single species, and must now recapitulate our results, in order to study 
the agreements or differences of the known species. A mere glance at one of our 
Plates will suffice to show any entomologist that, in comparison with the consider- 
able variations which occur in a single species, the differences which separate one 
species from another are often very slight—so slight that in our comparative 
descriptions we are obliged constantly to use such expressions as “a little more 
or less,” “ very similar,” “ very closely allied,” &c.; while some differences are so slight 
that, although perceptible to the eye, they cannot be expressed in words. Our figures, 
like our descriptions, cannot attain the acme of perfection, an absolute facsimile of a 
specimen being practically unattainable. 
