On Aquatic Carmvorous Coleoptera or Dytiscida. 635 
and do not reach the tropics. They are of large stature, and may be arranged in 
four groups as follows :— 
Group 1.—Labrum distinctly emargmate in middle; apices of coxal processes 
not spinose. Nos. 983 to 994. 
Group 2.—Labrum distinctly emarginate in middle ; apices of coxal processes 
acutely spinose. Nos. 995 to 1,002. 
Groupe 3.—Labrum truncate in middle ; apices of coxal processes acutely spinose ; 
mareins of elytra dilated. No. 1,003. 
Grour 4.—Labrum nearly truncate in middle ; apices of coxal processes obtuse ; 
margins of elytra nearly simple. No. 1,004. 
Group I. 
983. Dytiscus punctulatus, Fab., M.C.—Nigro-piceus, prothoracis elytrorumque 
lateribus flavo-marginatis, antennis rufis ; angustulus, elytris posterius crebrius punc- 
tatis; pedibus gracilibus, femoribus posterioribus dense subtilissime punctulatis ; 
prosterni processu acuminato, sat elongato ; coxarum processubus rotundatis ; elytris 
versus latera ultra medium longitudinaliter impressis. Long. 29, lat. 14 m.m. 
Mas, nitidus. 
Fem., subopaca, crebrius punctulata, elytris ad basin ultra medium suleatis. 
In the male the small palettes of the front and middle tarsi are excessively small, 
so as to have a spongy appearance. 
This species is readily distinguished by the dark undersurface, the slender hind 
legs, and rounded coxal processes, and the greater than usual punctuation of the 
elytra. The differences between the two sexes are great and constant. Inthe female 
the eighth interstice is always greatly abbreviated and is broken up into granules 
at its termination. The species seems subject to little variation except in size. 
Northern and Central Europe, (Sweden, Britain, Northern France, Geneva, Germany). 935. 
984. Dytiscus sharpi, Wehncke, Stet. Ent. Zeit. 1875, p. 500.—Latiusculus, 
supra parum convexus, nigro-piceus, parum nitidus, prothoracis ely trorumque lateri- 
bus flavo-marginatis, pedibus piceis ; elytris versus apicem minus subtiliter et con- 
fertim subrugoloso-punctatis ; femoribus posterioribus maris crebre subtiliterque sed 
conspicuiter punctatis ; coxarum processubus rotundatis. Long. 30, lat. 16 m.m. 
I have seen but a single male individual of this species, which appears to be a 
very distinct one. It agrees with Dytiscus punctulatus in colour, and the shape of 
the coxal processes, but differs from it in form, punctuation, and in the greater size 
of the small palettes of the frent and middle tarsi of the male; in this later respect 
it resembles D. dimidiatus. The lateral yellow band of the elytra becomes oblite- 
TRANS, ROY. DUB. SOC., N.S., VOL, Il. 4 N 
