686 On Aquatic Carnivorous Coleoptera or Dijtiscid<e. 



contrast comparatively slightly with them ; the middle tarsi bear two rows of small 

 sessile palettes. The female has no peculiar sculpture. 



The species is a variable one in size, and most inconstant in the markings of the 

 upper surface ; the transverse bands are liable to increase or diminution of size, 

 and become very irregular so as to send off more or less developed longitudinal 

 prolongations ; sometimes the posterior band is so much diminished as to be 

 represented only by some incompletely connected longitudinal marks. The thoracic 

 marks also vary much ; the transverse bands on it are larger or smaller, and are 

 connected together by a central point, and when these marks take their largest 

 extension, the prothorax is black with the sides broadly yellow ; the head is more 

 constant in colour, it being yellow with the extreme vertex black, this black 

 colour being prolonged in front along the margin of the eye ; it is very rare for there 

 to be any dark mark on the middle of the head, but in a remarkable variety found in 

 the island of Timor, there are on the middle of the head two black marks placed 

 at an angle to one another ; this variety (Hydaticus chevrolati, Aube) has the black 

 bands of the elytra formed of largely developed longitudinal portions, more or less 

 incompletely united. 



Eastern tropical Asia, (India, Laos, Bangkok, Cocliin China, China, .Java, Timor). 978. 



1074. Dytiscus festivus. 111., Hydaticus festivus, M.C. — Ovalis, parum latus, 

 nitidus, subtus piceus, supra testaceus, vcrtice, maculis duabus in fronte, prothorace 

 anterius et posterius in medio, elytris sutura, fasciis duabus transversis a prolonga- 

 tionibus longitudinalibus plus minusve connexis, nigris ; antennis pedibusque 

 anterioribus testaceis, pedibus posterioribus piceis. Long. 14, lat. 8 m.m. 



This species is distinguished from Sandracottus hunteri by its rather narrower 

 and more parallel and less convex form, and the greater development of, and 

 communication between, the black marks on the elytra, so that it is, jierhaps, not 

 a distinct species ; the two black marks on the middle of the head are always 

 present, and the transverse band on the middle of the elyti-a sends off in front a 

 longitudinal prolongation, perfectly parallel to the suture, so that a longitudinal 

 parallel-sided yellow mark extends from the base to the first band ; the black colour 

 of the suture always takes, near the apex, a development in the transverse direction, 

 so as to form a subapical blotch. 



India, China, Ceylon. 979. 



1075. Hydaticus dejeani, Aube, M.C. — Ovalis, parum latus et convexus, Isevigatus, 

 pernitidus, subtus piceus, supra capite, thorace elytrisque conspicue nigro flavoque 

 pictis, antennis pedibusque anterioribus testaceis, pedibus posterioribus nigricantibus, 

 femoribus rufescentibus. Long. 12i, lat. 7«, m.m. 



This species Is possibly not distinct from Dytiscus festivus, and, if so, may be 

 probably only a variety of Sandracottus hunteri ; it is always, however, smaller than. 



