On Aquatic Carnivorous Coleoptera or Dytiscidce. 635 



and do not reach the tropics. They are of large stature, and may be arranged in 

 four groups as follows : — 



Group 1. — Labvum distinctlj' emarginate 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. 99.5 to 1,002. 

 Group 3. — Labrum truncate in middle ; apices of coxal processes acutely spinose ; 



margins of elytra dilated. No. 1,003. 

 Group 4. — Labrum nearly truncate in middle ; apices of coxal processes obtuse ; 



margins of elytra nearly simple. No. 1,004. 



Group 1. 



983. Dytlscus 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 acuminate, sat elongato ; coxarum processubus rotundatis ; elytris 

 versus latera ultra medium longitudinaliter impressis. Long. 29, lat. 14 m.m. 



Mas, nitidus. 



Fern., subopaca, crebrius punctulata, elytris ad basin ultra medium sulcatis. 



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. In the 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 elytrorumque 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 front and middle tarsi of the male ; in this later respect 

 it resembles D. dimidiatus. The lateral yellow band of the elytra becomes oblite- 



TBANS. EOr. DUB. SOC, N.S , VOL. II. 4 N 



