412 PE. F. LEUTIDfEB, ON THE ODONTOLABINI. 



(ii.) Group ofO. stevensi. (Plate XC.) 



The connection between the black male and the bicolorous female of 0. stevensi from 

 Celebes was long suspected, but not proved until the discovery of the closely allied 

 0. duivenhodii, in which the elytra are tricolorous in both sexes, and which occurs in the 

 neighbouring island of Sangir. But the latter coloration is not exactly new, for it arises 

 from the disappearance of the black jjigment on the middle of the elytra, as in JVeolu- 

 canus cingidatus ( 2 ). Notwithstanding the differences in the prothorax (figs. 7, 8), the 

 males exhibit much similarity in the structure of the head, and in the form of the 

 mandibles ; but in the largest forms (figs. 5, 6) the latter are differentiated, so that in 

 the latest evolved species they are apparently more simplified than the parent species, 

 and resemble those of 0. alces, var. dux. 



(iii.) Group of O. burmeisteri. (Plates XCI., XCII.) 



This group comprises a very natural assemblage of species — (1) 0. sinensis (China), 

 (2) 0. mouhoti (Siam), (3) 0. cnvem (N. India), (4) 0. delesserti, and (5) 0. bur- 

 meisteri (Travancore). Their common origin is palpable, both sexes being equally 

 differentiated. Their differences, however, depend more on colour than on form. 

 In the group of 0. alces the uniform black colour of the elytra, especially in the 

 females, renders their determination a task of great difficulty ; but in the present 

 group it is more especially the females which enable us to separate the species satis- 

 factorily by their characteristic and constant markings. In 0. sinensis (PI. XCI. fig. 4) 

 there is only a narrow reddish-brown border to the elytra, both above and below. In 

 0. cuvera (PI. XCI. fig. 10) this is pale brownish-yellow, and much broader, but the 

 under-surface of the rim of the elytra is always black. This is also the case in the 

 much lai'ger female of 0. delesserti (PI. XCII. fig. 4), whereas in the female of 0. bur- 

 meisteri (PL XCII. fig. 9), in which the black portion of the elytra is still narrower, 

 the under-.surface of the recurved rim of the elytra is again yellow, as in 0. sinensis. 

 The male and female of each species agree in the colour and markings of the elytra, but 

 the under-surface is frequently different. Thus it is in 



Male. Female. 



0. sinensis yellow yellow. 



0. mouhoti yellow ^ 



0. cuvera yellow ..... black. 



0. delesserti black black. 



0. burmeisteri .... yellow yellow. 



Whether this enables the sexes to recognize each other, as it enables us to separate 

 the species, cannot be decided. 0. sinensis (PI. XCI. figs. 1-3) and 0. cuvera (figs. 7-9) 

 agree in the forms of the male mandibles, and in the strong spines of the front tibiae. 



