Water Beetles of Japan. 63 
siibtiliter punctulatis ; elytris striato-punctatis, striis in- 
ternis subtilioribus, palpis tarsisque testaceis. Long. 1^ — 
2 lin. 
Maxillary palpi yellow, last joint longer than the pre- 
ceding one ; the antepenultimate joint distinctly thickened. 
Head very broad, margined along the front, densely and 
finely punctured, especially in front, and with some irregu- 
larly placed larger punctures. Thorax densely and rather 
finely punctured, with a few indistinct larger punctures 
scattered about it. Elytra externally with some rows of 
coarse punctures ; the internal ones are very fine, and only 
to be seen towards the extremity, where it is found that 
the rows are placed obliquely, so that the inner ones end 
near the suture some distance before the apex ; the ex- 
ternal interstices have each a row of coarse punctures, and 
also some finer punctures. The underside has only an 
extremely sparing and fine, scarcely visible, pubescence. 
The legs are yellowish or pitchy yellow, the tarsi yellow, 
the posterior tarsi slender, and not at all remiform. The 
intermediate cox£e are considerably separated, the meso- 
sternum not carinate. 
Taken at Hiogo and Nagasaki. 
This insect is one of great interest from a pecuHar struc- 
ture of the abdomen, which has not yet been remarked. 
On the abdomen being taken off it is found that the first 
segment 'is placed at right angles with the others (the 
abdomen is perhaps flexible there), so that in life the 
hinder segments are tm^ned upwards, and leave a large 
vacant space underneath the elytra. In one large speci- 
men I have examined, no doubt a female, the abdomen at 
first sight appears to be entirely wanting. It is very pos- 
sible that this structure enables the insect to carry about 
its eggs on dry land ; it is, I have no doubt, at best only 
a semi-aquatic species, for it is not provided with ]3ubes- 
cent portions on the under surface to retain air, as are the 
more aquatic palpicorns. This peculiar abdominal struc- 
ture must be considered in connection with the inflated 
elytra, and also with the fact that the hind coxse are trans- 
verse and largely developed, and free both above and 
below ; add to this, that where the posterior legs are 
flexed an additional protection is given by them to the 
subelytral space. Observations on the habits of this spe- 
cies would, I have no doubt, be of great interest. 
I am indebted to Mr. H. W. Bates for a closely allied 
