*\ 



96 Memoirs of the Indian Museum. [Vol. VII, 



f Grooves 5-7 of elytra somewhat variable in width ; the posterior 



1 part of groove 8 rarely wider than the anterior part, never 



as wide as groove 7 ; insects at most about 45 mm. long . . P. monticidosus, p. 95. 

 Grooves 5-7 of elytra always very broad ; the posterior part (and 

 sometimes the whole) of groove 8 like them ; insects at least 

 about 45 mm. long . . . . . . . . P. tridens, p. 95. 



Genus PLESTHENUS, Kaup, 187 1, p. 4 o. 



Type, Eriocnemis quadricomis, Kaup, 1868a, p. 26. 



Of the four species referred by Kuwert (1898, pp. 324-5) to the genus Pies thenus one, 

 lo'tini, Boisduval, probably belongs to an Australian genus, 1 the other three being 

 Celebean (see above, p. 76, footnote 2). Of these three invitus, Kuwert, is the most distinct. 

 This species is represented in the Van de Poll collection by perhaps three specimens. 

 Each of them is, however, distinguished by some definite character from the others ; and at 

 least two localities are represented by the three specimens, one of which bears no locality 

 record. It is impossible, therefore, to be certain at present whether the three specimens 

 belong to three separate species or not ; and it will probably be best to describe all under 

 the one specific name, referring at the same time to the individual differences. 



The other two species, quadricomis, Kaup, and gelon, Schaufuss, are together 

 represented by eleven specimens from five localities, two in the north of the island and 

 three in the south. The southern specimens are distinctly larger than the northern, and 

 they have an acuminate or very obliquely truncate right outer tubercle, the left outer 

 tubercle being more or less obsolete ; in the northern specimens, on the other hand, the right 

 outer tubercle tends to be more abruptly truncate, and the left outer tubercle to be more 

 strongly developed, in some instances much more so. Here again it seems impossible to 

 determine with certainty how many species are represented in the material before me, the 

 differences between different forms being in this case undoubtedly correlated with locality. 

 I propose, therefore, to treat all as a single species quadricomis, recognizing qe^.on as a more 

 or less distinct southern race. The races seem to be distinguished more definitely by size 

 than by structure. 



I am unable to identify any of the specimens before me with either of the species 

 described since Kuwert' s work was published (see above p. 9), but it is possible, I think, 

 that these may prove to be no more than varietal forms of P. quadricomis. 



Plesthenus invitus, Kuwert. 

 Pi. I. 



Plesthenus invitus, Kuwert, 1898, p. 325. 



Three specimens, one of which is from Tondano, Minahassa and another from Menado. 

 Both the specimens whose localities are recorded are 45-5 mm. long ; the other specimen is 

 much bigger, being 53 mm. long. 



This species differs from Pelofides burmeisceri, monticulosus and tridens only in the 

 generic character smentioned above (p. 79), in having the left anterior lower tooth wholly 

 distinct from the lowest terminal tooth instead of partially fused with it, and in the weaker 



1 Presumablj' Mastochilus . 



