On Aquatic Carnivorous Coleoptera or Dytiscide. 345 
Group 3.—Short broad species without pubescence, but with a most remarkably 
sculptured surface, the punctures on the under surface being especially 
large, the plica at the base of the thorax is continued on to the 
elytra in so conspicuous a manner that it forms a sort of elongate- 
carina extending half the length of the wing cases. Species 247 to 
254. 
Group 4.—Hind coxae not longer than broad ; surface not entirely glabrous, 
plica on elytra not extending one-half of length of the wing cases ; 
under surface with an extensive development of moderately coarse 
punctuation. Species 255 to 268. 
N.B.—The species placed at the end of this group connect it with 
the following one. 
Group 5.—Hind coxe longer than broad, under surface with but little coarse 
punctuation, apex of elytra but little acuminate ; elytra with a basal 
plica, which is continued (except in two species, Nos. 291 and 292), 
on to the base of the elytra either as a short punctiform impression 
or as a distinct line. Species 269 to 325. 
This group is further sectionized thus :— 
A. Each wing case provided with a distinct sutural stria. Species 269 
to 292. 
B. Wing cases destitute of a distinct sutural stria. Species 293 to 325. 
Group 1. 
242. Hydroporus cribrosus, Schaum, M.C.—Ovalis, brevis, latus, convexus, elytris 
creberrime fortiter punctatis, vix nitidis; pectore crebre eequaliter fortiter punc- 
tato. Long. 23, lat. 14 m.m. 
Egypt, (Cairo). 98. 
243. Bidessus migrator, n. sp.—Ovalis, brevis, latus, convexus, elytris crebre 
fortiter punctatis, subnitidis ; pectoris lateribus fortiter, medio obsolete, punctatis. 
Long. 2, lat. 1¢ m.m. 
Very closely allied to Hydroporus cribrosus, Schaum, but rather narrower, and 
with the punctures on the elytra not quite so close, and slightly coarser: the punc- 
tures on the hind coxe are finer, and those on the middle of the sternum much 
finer than in the Egyptian species. 
Australia, (Rockhampton). 99. 
