414 DK. r. LEFTHNEE ON THE ODONTOLABINI. 



are rounded, and less strongly curved. The diminution in the spines on the front tibise 

 in 0. delesserfi proceeds further in 0. burmeisicri, and they may even disappear 

 entirely in the telodont form. This and the great variability of the extreme form, 

 combined with geological facts, render it probable that we are dealing with a younger 

 offshoot in which the characters have not become so stable as in the northern species. 



The occurrence of the two last species in the same localities may lead to the 

 production of hybrids, for I have seen individuals which it was difficult to assign to 

 either species. This applies both to the small males and to female specimens. 



The differences between the species of this group are so slight that Prof. Westwood 

 regarded them as only geographical varieties. A large amount of material has enabled 

 me to separate them (comp. antea, p. 9). But it is obvious that continental species can 

 never be so sharply defined as insular species. 



The great similarity of the females and the uniform character of the coloration of 

 the elytra bridge over the gap between the continental Indian hurmeisten group and 

 the insular wollastoni group. 



(iv.) GroMpo/O. wollastoni. (Plates XCIIL, XCIV.) 

 The males of this group are distinguished by the luxuriant development of their 

 mandibles, and by the strongly marked and coarsely shagreened sculpture of their 

 broad heads. The species here admitted are — (6) 0. wollastoni, (7) 0. vollenhoveni, 

 (8) 0. ludekingi, and (9) 0. lacordairii, which inhabit Malacca, Sumatra, and Borneo. 

 The two first species agree in the shape of the mandibles, and are only distinguished 

 by their different colour. In 0. wollastoni, which occurs in Malacca and Sumatra, 

 the black triangular patch on the elytra is broad, nearly as in 0. cuvera, but is less 

 constant in form, and either extends in a point to the tip of the elytra (PI. XCIII. 

 figs. 5, 6), or it is broader (fig. 7), and ceases suddenly before the tip (in Parry's tj'pe) as in 

 0. sinensis (PI. XCI. fig. 1 c). In the Bornean 0. vollenhoveni (PI. XCIII. figs. 1-4) 

 it is reduced to a narrow black stripe on the suture ; but the head is marked with red 

 in the male, which immediately distinguishes it from the preceding species. It occurs 

 in south-eastern Sumatra in company with 0. lacordairii (PI. XCIV.). In 0. lacor- 

 dairii the red colouring is more extended, not being limited to the elytra, but occurring 

 on the pectus and on the under-surface of the femora in the male, and on the prothorax 

 in the female. 0. ludekingi is distinguished by a narrow pointed stripe on each of the 

 elytra ; but only a few specimens are known. It occurs in the same locality as the two 

 preceding species. Its peculiarly shaped mandibles, of which only small forms are 

 known with certainty (PI. XCIII. figs. 10, 11), at once resemble those of 0. lacordairii 

 (compare PI. XCIII. figs. 10, 11, with PI. XCIV. figs. 3, 4 c) and 0. wollastoni, which, 

 together with the two differently coloured females of 0. lacordairii, render it probable 

 that it is a hybrid between 0. tvollastoni and 0. lacordairii. 



