On Aquatic Carnivorous Coleoptera or DijtiscidcB. 657 



antei-ioribus rufis ; tarsorum posticorum ciliarum raargine anteriore semper valde 

 arciiato, fere angulato. Long. 16, lat. 9i lu.ui. 



The male has the front tarsi largely developed, both fringing hairs and palettes 

 being large ; the female sometimes has the thorax smooth, and sometimes its lateral 

 portions bear numerous irregular impressions. 



The species is a very variable one, and shows numerous local but indefinite varia- 

 tions. The commonest form is one of large size, in which the transverse band near 

 the base of the wing-cases is slender, the lateral mark behind the middle is small 

 and broken up into two or three spots, and the subapical mark is indistinct, all these 

 yellow marks being more or less dotted with black. This form is found with greater 

 or less extension of the yellow marks, in Malacca, the Philippine Islands, Andaman 

 Islands, Celebes, Amboyna and Timor: and is the Hydaticus paciticus, Aube. 



The second form is much smaller in size, and has the yellow marks on the wing 

 cases large and definite, the lateral yellow mark beyond the middle takes a great 

 extension towards the suture, so that it forms a once or twice interrupted transverse 

 fascia, the subapical mark is a distinct yellow spot. This form is the Hydaticus 

 bihamatus of Aube, and is peculiar to the Philippine islands, but I have specimens 

 from Malacca which quite connect it with the first form. 



The specimens from the Andaman Islands are a peculiar variety of the first form, 

 being rather small, slender and depressed, with unusually slender posterior tarsi, 

 and with a diminished development of the cilise on the hind margins of their joints. 



Malacca, Andaman Islands, Philippiues, Celebes, Amboyna. 1025. 



1022. Hydaticus luczonicus, Aube, M.C. — Ovalis, satconvexus, capite thoraceque 

 testaceis, illo vertice signaturaque inter oculos plus minusve discreta, hoc in medio 

 ab apice ad basin nigricantibus ; elytris vix ex parte majore nigris, vitta transversa 

 subbasali margineque laterali lato testaceis, margine hoc nigro-irrorato ; subtus 

 nigro-piceus, pedibus quatuor anterioribus antennisque rufis. Long. 14i, lat. 

 8\ m.m. 



This species is very closely allied to the preceding, but is distinguished by its 

 colour, the wing-cases bearing two longitudinal zones of colour of about equal 

 areas, the inner one black, the outer yellow dotted with black ; the outer yellow 

 zone of colour sends off near the base a transverse line which is continued 

 towards the suture till it nearly reaches the scutellum. The female has some 

 coarse impressions on the lateral part of the thorax. 



Philippine Islands ; India. 1024. 



1023. Hydaticus dineutoides, n. sp. — Latus, subdepressus, niger, supra opacus, 

 glaucus, vix senescens, clypeo breviter flavo, antennis rufis. Long. 15, lat. 

 8i m.m. 



