On Aquatic Carnivorous Coleoptera or Dytiscide. 657 
anterioribus rufis; tarsorum posticorum ciliarum margine anteriore semper valde 
arcuato, fere angulato. Long. 16, lat. 94 mim. 
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 pacificus, Aubé. 
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 formsa 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 cilize on the hind margins of their joints. 
Malacca, Andaman Islands, Philippines, Celebes, Amboyna. 1025. 
1022. Hydaticus luezonicus, Aubé, M.C.—Ovalis, sat convexus, 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 hoe nigro-irrorato ; subtus 
nigro-piceus, pedibus quatuor anterioribus antennisque rufis. Long. 143, lat. 
84 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 ot the thorax. 
Philippine Islands ; India. 1024. 
1023. Hydaticus dineutoides, n. sp.—Latus, subdepressus, niger, supra opacus, 
glaucus, vix znescens, clypeo breviter flavo, antennis rufis. Long. 15, lat. 
84 m.m. 
