DR. F. LEUTHNER ON THE ODONTOLABINI. 399 
series, like the teeth of a saw (woodcut, fig. 2, no. 1). If the mandibles are only 2 or 3 
millim. longer, the teeth are divided into two groups by a little gap rather beyond the 
middle (no. 2). The gap is more distinct in no. 3, where the mandibles are only 
1 millim. longer than in the preceding; in no. 4 they become larger and larger, so that 
the eight originally uniform teeth are divided into two series—one of five (subsequently 
four) at the tip, and another of three at the base of the mandibles (forma amphiodonta). 
Fig. 2. 
apie: 
Modifications of the mandibles in Odontolabis alces, Fabr. 
2; no. 1 , forma priodonta; nos. 2-5, forma amphiodonta (cumingi, Hope); no. 7, forma mesodonta 
(alees, Fabr.); no. 9, forma telodonta (dua, Westw.) ; nos. 6 and 8, intermediate connecting links. 
The three obtuse teeth at the base are at first uniform (cumingi, fig. 4), but in 
no. 5 the first tooth has already become more prominent. The larger the mandibles, 
the larger this tooth becomes by inward expansion, while the two teeth at the base 
may remain. Among a number of specimens I found several which had only one small 
tooth at the base (no. 6), while the more strongly developed central tooth projected 
inwards and downwards like a conical appendage to the mandibles. In these large 
specimens the five apical teeth are generally reduced to four (no. 7); at the same time 
the mandibles become gradually more curved and rounded; the tip only remains flat- 
tened and compressed. If the last rudimentary basal tooth disappears, we get the true 
mesodont form, in which a strong central tooth projects inwards rather beyond the 
middle (alces, Fabr., no. 7). My materials from Manilla enable me to trace the 
gradual and unbroken differentiation of the mandibles to this point. In the form 
with longest mandibles (dux, Westw.) the middle tooth is entirely wanting (no. 9), 
and we find nothing but the four small apical teeth (forma telodonta). 
