Water Beetles of Japan. 49 
teriore (vel interiore) leviter dilatato ante basin emargi- 
nato. 
This very distinct and interesting Agabus is allied to 
both A. bipustulatus and fuscipennis, while in the struc- 
ture of the claws of the hind feet it makes an approach to 
Ilybius. It is readily distinguished from fuscipennis by 
the larger size and the rounded base of the thorax, as well 
as by the distinct reticulation of the elytra. It is broader 
and more rounded at the sides than is A. bipustulatus, 
and the reticulation of its upper surface is quite different 
from that species, being much finer, and the direction of 
the lines transverse rather than longitudinal ; the sculp- 
ture of the under surface much resembles that of bipustu- 
latus. The shape of the lateral lacinise of the metaster- 
num is rather close to tha.t of A. ftiscipennis, but the depth 
of the hind coxse is considerably more than in fuscipennis ; 
this arises both from their upper margin being more 
strongly arched, and their lower margin more transverse 
(that is, less oblique in direction) than in fuscipennis. 
The claws of the hind tarsi are closely applied to one 
another, and almost straight, the outer one is evidently 
smaller than the inner one ; the disparity, however, is 
much less than in Ilybius. The species is rather variable 
in its colour. 
Osaka and Nagasaki. Common. 
12. Ayabus (^Platambus,Th..) pictipennis,n.sp. Ovalis, 
supra nitidissimus, nigricans, capite maculis duabus, an- 
tennis pedibusque rufis; elytris basi fascia ad scutellum 
inteiTupta et utrinque versus latus maculis tribus pallidis ; 
prothorace angulis posterioribus subacutis ; subtus ferru- 
gineus. Long. 3^ lin. 
Mas, tarsis anticis vix dilatatis, unguiculis simplicibus. 
This species has all the structure assigned by Thomson 
to the genus Platambus. It is readily distinguished fi-om 
A. maculatus by the shining and nearly unsculptured 
upper surface, as well as by the different markings ; in 
this latter respect it appears more allied to A, sinuatus, 
Aube (from Asia Minor), a species which I have not seen, 
but which, judging from description, should be similar in 
sculpture to maculatus, and therefore very different from 
pictipennis ; sinuatus has, moreover, at the sides of the 
elytra a continuous pale band instead of the three spots of 
TRANS. ENT. SOC. 1873. — PART I. (mAR.) E 
