944 On Aquatic Carnivorous Coleoptera or Dytiscide. 
Wale ID SW INMISIIS INS, (0 1s 1.18 18; S,) 
II]. 1.—Tribe NOTERIDES. (Vide p. 260.) 
This tertiary aggregate consists of two groups and two isolated genera, and 
comprises altogether only about eighty species, arranged in nine genera. The size of 
the individuals, occasionally very minute and never large, ranges from 1 to 8 m.m. 
of length. The form is peculiar, the convexity is great, but is nearly limited to the 
upper surface; the thorax and elytra are excessively co-adapted, and thus 
perfectly continuous in outline; this outline is attenuate or acuminate behind. 
Variegation of colour only occasionally becomes conspicuous, the punctuation of 
the surface may be considerable, or on the upper surface may be wanting, giving 
place to an extreme polish. The head is short, never in the least margined in 
front, but terminating in a sharp edge, so that the very exposed labrum continues 
the plane of the upper surface of the head; the eyes are never very prominent, 
and their circular outline is a little notched by the side of the head over the 
insertion of the antenna. The antennz are short, and the shape of the joints is 
more or less dissimilar inter se; the labial palpi usually have the terminal joint 
dilated, and frequently notched. The prothorax has always a lateral margin, which 
is often very broad and very little elevated. The front coxee are conical in form 
in some genera (Notomicrus, Hydrocoptus, Noterus), but approach more nearly to 
the spherical form than in the other Dytiscidze, and in Suphisini and Hydrocanthini 
they are nearly truly globose ; Pronoterus and Synchortus being apparently inter- 
mediate forms in this respect. The prosternum along the middle longitudinally, 
is usually of one plane from the front margin to the termination of the prosternal 
process, but in Colpius, it is inerassate in this direction, so that it projects beyond 
the coxze, and forms a conspicuous prominent rectangle: the length of the pro- 
sternum in front of the coxz is sometimes extremely little (Suphisini), sometimes 
moderately great, (Noterus, Hydrocanthus) ; the prosternal process varies greatly, 
but it has never a slender acuminate terminal portion, and is usually very large, 
and becomes broader behind ; when small it is broad in proportion to the length ; 
it is always received into a highly developed fork of the mesosternum, and its 
posterior edge is extremely accurately co-adapted with the anterior part of the 
inter-coxal process of the metasternum. 
The front legs are in the more differentiated forms of the Noterides modified in 
a remarkable manner, the modification reaches its extreme in the Suphisini and 
Aydrocanthini, but little or no trace of it can be found in Notomicrus and Hydro- 
coptus. The femora in Suphisini become subcylindric and a little arcuate, and 
the tibia assumes a position in which the normally upper face looks outwards; this. 
part of the leg is at the same time modified in shape, and terminates in a large 
hook; this hook is one of the ordinary spurs of the apex of the tibia developed in 
