On Aquatic Carnivorous Coleoptera or Dytiscide 715 
Group 1. 
1119. Dytiscus fimbriolatus, Say, 7) ogus fimbriolatus, M.C.— Ovalis, supra niger, 
subolivaceus, capite anterius prothoraceque lateribus testaceis, elytris vitta laterali 
posterius obsoletescente testacea; corpore subtus piceo, abdominis lateribus flavo- 
maculatis, antennis pedibusque anterioribus rufis, pedibus posterioribus tarsisque 
intermediis piceis. Long. 282, lat. 16 m.m. 
The male has a narrow excessively obscure band of extremely short sexual 
pubescence, on the undersurface of the basal joint of the intermediate tarsus ; and 
the hind coxa has at the apex just in front of the articulation three or four coarse 
plice. The female is without these folds; but has a well marked sexual sculpture 
on the upper surface, there are always some fine scratches on each side of the back 
of the head, and the thorax has numerous irregular scratches, while the elytra are 
generally covered with longitudinal scratches, anastomosing here and there, and 
leaving only a small space at the apex, and a band along the suture smooth: the 
epipleurze, just behind the shoulder, are broader than in the male, and are flattened, 
and obliquely perpendicular, instead of being rounded, and transverse in direction, 
as they are in the male. 
The species appears to be very variable, and it is quite possible that there will 
prove to be more than one distinct form mixed under its name; the yellow band 
on the side of the elytra is rather narrow, and at the apex is indefinite, indeed on 
the hinder half of the wing-case a line of darker colour separates the yellow line 
from occupying the outer margin, this darker band is not often very definite ; at 
the apex at a distance from the suture there are some yellow macule, which when 
more than usually distinct give to the yellow marginal band the appearance of 
being dilated there. Ina variety from Texas, the lateral band of the elytra is 
broader, and reaches in a definite manner to the suture, where however it is 
thinned out to a point. The sexual sculpture of the female also varies much ; the 
scratches on the head are always present, and sometimes the scratches on the 
thorax and elytra are coarse and close, while in certain individuals they become 
finer, shorter and more isolated, and at the same time occupy a less area on the 
wing-cases, their disappearance being from the apical and sutural portions. The 
supplementary obsolete claw of the female hind tarsi also varies in its development, 
being sometimes so small as to be not very easily detected, while in other cases it is 
longer, more detached, and more conspicuous, it appears to be most largely deve- 
loped in those cases where the terminal joint of the tarsus is shortest and thickest. 
Besides these points of variation, considerable difference is also found in size and 
colour, and even in the extent of the development of the sexual pubescence on the 
intermediate tarsi of the male, the band on the basal joint being sometimes larger, 
TRANS, ROY. DUB. SOC., N.S., VOL, II, 4Z 
