480 Mr. G. J. Arrow on 



The genus Farastasia was originally cbaracterised by 

 Westwooil, as he says, "from a female of P. canaliculata 

 and a male of P. Westiuoodii," those sexes of the two species 

 alone being known to him. These two insects represent 

 in a wide sense the opposite extremes of this comprehen- 

 sive, but sufficiently well-defined, genus, and between them 

 may be ranged forms which have hitherto been regarded 

 as constituting different generic types. As might be 

 expected therefore, the generic characters so far as they 

 are sexual, are wholly incorrect. The male of P. canalicur 

 lata has remained unknown, Dr. Ohaus stating that he 

 knows only females, whilst two specimens, besides the 

 type (which I have been able to examine), are also females. 

 Another insect liowever, P. bijmndata, described by West- 

 wood from the same collection of Philippine beetles, con- 

 sists only of males, all the specimens in the British 

 Museum, including the type, being of that sex, and Dr. 

 Ohaus also indicating that the female is unknown to 

 him. The two insects are similar in form and size, the 

 chief differences being that the body, especially the 

 prothorax, is more parallel-sided in the first (P. canaliculata, 

 of Westvvood), the propygidium not shining, and especially 

 that a part of the yellow fascia is elevated above the 

 general surface of the elytra and has a deep groove on 

 each side of the scutellura. All these peculiar features, 

 in view of those which will be leferred to in other species, 

 seem to point to the fact that the two are the sexes of the 

 same species, and looking at all the evidence I have no 

 hesitation in stating this to be the case. In the structure 

 of the claws, as in other features by which the sexes of 

 Rutelidse are usually distinguished, these two forms are 

 practically identical, nor are the remarkable differences 

 which I have mentioned, like others which I shall refer to 

 later on, known to occur in any form in any other group. 

 The genus Parastasia is therefore highly peculiar, and 

 indeed other structural features show it to occupy a very 

 isolated position. 



Pao'astasia canaliculata, the type of the genus (vide the 

 original description, Ann. Nat. Hist., 1841, viii, p. 204) 

 belongs to the 3rd group of Dr. Ohaus, forming the pre- 

 ponderating section of the genus, in Avhich there is no 

 constant external character distinguishing the sexes, but a 

 variety of differences in different species. In P. rufopicta, 

 an insect closely related to the previous one, a remarkable 



