On Aquatic Carnworous Coleoptera or Dytiscide. 671 
q | 
certain individuals there are quite distinct short irregular unpressions, while in other 
cases there is in the same situation only a more dense and, perhaps, rather coarser 
punctuation, while often there seems to be no departure from such punctuation as 
exists in the male. 
The species is easily recognised by the yellow vitta running parallel with the 
outer margin of the wing case, and extending from the base to near the apex, but 
not there attaining the suture; and by the short additional humeral vitta: both 
these stripes are subject to some variations, the elongate one is sometimes inter- 
rupted, or broken up, and, very rarely, nearly entirely absent; the outer yellow 
stripe also varies somewhat ; it is often so confluent with the more elongate stripe 
that the two have the appearance of one stripe enclosing a small humeral black 
mark: this black mark may become more elongate so that the junction of the two 
yellow stripes occurs only just behind the middle; in other cases the short humeral 
stripe does not join the inner stripe at all, but is terminated just before the middle. 
The species also varies somewhat in size and form: it has always the ciliz of 
the hind margins of the joints of the posterior tarsi very largely developed, but even 
this is subject to a little variation. ‘The variations are to some extent, but only 
slightly, dependent on geographical distribution; the most marked instance of 
which is that the specimens in which the short humeral yellow stripes on the wing- 
cases remains quite ununited with the longer stripe, occurs chiefly in Australia: 
similar individuals occur, however, in Siam and the Malay peninsula, and every 
grade of intermediate character may be found. A variety from the Philippine 
Islands has the inner yellow stripe represented only by a spot of that colour near 
the apex of the wing-cases, the humeral stripe being on the other hand a little 
longer than usual, this has been recently described as a distinct species (H. 
bipunctatus, Wehncke). 
This species is very widely distributed in the South Eastern parts of the Old World. Japan, 
Mantchuria, Formosa, China, East India, Ceylon, Malacca, Siam, Java, Borneo, Sumatra, Celebes, 
Philippine Islands, Labuan, Batchian, Menado, and Australia (North, South, and West). 1044. 
1050. Hydaticus exclamationis, Aubé, M.C.—Ovalis, sat latus et convexus 
niger, capite anterius prothoraceque ad latera testaceis, elytris vitta elongata lateral 
testacea ; antennis pedibusque anterioribus testaceis, pedibus posterioribus piceis. 
Long. 134, lat. 8 m.m. 
This species differs from Dytiscus vittatus, inasmuch as the short humeral stripe 
of the elytra of that species is in the present one extended to the extremity of the 
wing-cases, while the inner stripe is entirely wanting; besides this the cilize on the 
hind margins of the joints of the posterior tarsi are much shorter, and the fringing 
hairs at the base of the anterior tarsi of the male are considerably longer than in 
