276 pnvTOPiiAGA. [D<*ta<-:a. 



D. clnerea, Herbsf. (JiyJrocharidis, F.). This species may be 

 distinguished from all the rest of the British Dunacice l>y having the 

 upper surface thickly clothed with greyish-silvery pubescence, so that 

 the insect presents a dull and mealy appearance; the only other 

 European species that resembles it in this respect is I), tomentosa ; the 

 under-side is silvery ; it is elongate, sublinear and depressed, of a 

 greenish or reddish coppery colour, with the antennae dark, the base of 

 the joints being more or less ferruginous, and the legs metallic, partially 

 ferruginous ; head and thorax very closely sculptured, the latter sub- 

 quadrate with the anterior angles scarcely prominent ; elytra subparr.llel, 

 widest about middle, with the apices rounded or very obtusely truncate, 

 feebly impressed on disc near suture, with comparatively finely punc- 

 tured striae, interstices closely rugose ; posterior femora simple in both 

 sexes. L. 7-10 mm. 



Male with the last ventral segment subtruncate at apex and impressed, 

 ft-male with the same segment rounded at apex. 



On aquatic plants, Sparganium, Typha latifolia, Arundo phragmites, &c.. in 

 May and June; rare; Woolwich; Surrey Canal; Woking (banks of Basingstoke 

 Ciinal) ; Faygate, Sussex ; Winchelsea ; Deal ; Swansea ;" Bristol ; Yorkshire ; 

 Northumberland district, Prestwick Carr (Wailes). 



D. sericea, L. (lavicollis, Thorns.; profeiis, Steph.). Convex, 

 rather short, broader in male than in female, upper surface shining, 

 rarely dull, strongly metallic, very variable in colour, presenting all 

 shades of coppery, greenish-coppery, aeneous, green, blue, blue- black, 

 crimson, &c. ; the base of the antenme and the legs are concolorous with 

 the upper side ; under-side silvery ; head thickly punctured, with the 

 frontal furrow deep, antennae rather long, with the third joint elongate, 

 twice as long as second ; thorax longer than broad, narrowed behind, 

 very closely sculptured, with the anterior angles acute and reHexed and 

 the lateral callosities strongly defined ; elytra broadest at shoulders, 

 distinctly impressed, with moderately strongly punctured striae, the 

 punctures being connected by transverse wrinkles, and the interstices 

 besides these being more or less distinctly rugose, apices rounded or 

 obtusely truncate ; legs moderately long, femora with a strong triangular 

 tooth in both sexes. L. 7-9^ mm. 



Male with the first ventral segment of abdomen broadly impressed at 

 apex, and the fifth impressed and truncate at apex, female with the fifth 

 segment rounded at apex. 



On aquatic plants; common and generally distributed from the northern midland 

 counties southwards ; less common further north ; Scotland, not common, Solway, 

 Tweed, Forth, Dee, and Moray districts ; Ireland, near Dublin and Armagh, and 

 probably widely distributed. 



X>. discolor, Panz. (comari, Suffr. ; proteus, Kunze ; geniculata, 

 Thorns.). Very closely allied to the preceding in shape, colour, and 

 general structure and sculpture ; it may, however, be easily known by 



