Rhantusi] aoepiiaga. 203 



Zl. adspcrsus, F. This species superficially very closely reseml)les 

 C. exvlelm, beinjf coloured like that insect on the upper side ; it is, how- 

 ever, rather ])roader, more widened behind, and more plainly reticulate : 

 it may at once be distinguislied by the colour of the under side, which is 

 tilack with the prosteruum, first segment, and apex, and hind margins of 

 (ither segments of abdomen testaceous, the breast also being redilish ia 

 tlie middle; male with the front tarsi considerably thickened and imt 

 much compressed with muderately large palettes underneath. Long. 9., 

 hit. 5 1 mm. 



Very rare ; lias only occurred near Cambridge, where it was found in 1829 in 

 numbers ; of late years it seems to have disappeared. 



Dr. Sharp in his collection has a specimen of Hydaticus Icander, Rossi, 

 given him by Mr. Crotch as a l»ritish example of M. adspersus. 



COIiVMBSTZlS, Clairvillc. 



This genus comprises about twenty species, -which are chiefly found 

 in the northern parts of Europe and Asia and in North America ; they 

 are nearly all over 15 mm. in length, and some reach to 18 or 20 mm. 



The larva and pupa of C.fusctis are figured by Schiodte (ii., PI. ii., Fig. 6, PI. iii., 

 Fig. 2) : the larva hears a resemblance to an elongated peg-top, like other of the 

 Dytiseide larvae, the eighth segment being very much elongated and cylindrical; ihe 

 head is rounded, narrower than prothorax, and furnished with strong simple man- 

 dibles ; the prothorax is very large with the margins broadly explunate and somewhat 

 rertexed ; the rest of the segments as far as the seventh, which is much constricted, 

 are very short ; the cerci which proceed from the end of the eighth segment ai-e rather 

 long, tiiickly ciliated and terminating in long seta;; the colour is pale yellow with a 

 thin fuscous line running down the centre of tbe scuta and a few other darker 

 markings at sides ; the claws are long, almost eijual, slightly pectinate at base. 



C< fuscus, L. Oval, rather elongate, moderately convex, underside 

 black ; head black, Avith front aud two spots behind retl ; thorax 

 fuscous Avith borders more or less l^roadly testaceous, elytra fuscous with 

 sides testaceous ; antennaa and anterior pairs of legs red with femora 

 pitchy, posterior pair blackish ; thorax finely strigose, elytra distinctly 

 transversely reticulate, with obscure wavy striation, with irregular rows 

 of larger jiunctures ; a])domen witli the second segment on each side 

 near middle with longitudinal wrinkles ; male with the basal joints of the 

 front and midiUe tarsi moilerately dilated and much compressed, and 

 furnished beneath witli four series of rather large, round palettes ; 

 sculpture of sexes identical. Long. 16, lat. 8} mm. 



Ponds, ditches, and slowly moving streams and small rivers; common and widely 

 distributed throughout the gri'ater part of England, Wales, ami Inland : not so 

 common in the north ; Seolhnul not common, ^but widely distributed, uud reachiu^j 

 as far north as the Orkney Islands. 



DYTISCINA. 



Tile meml)ers of this tiilte arc cliaraeteriztd by luiving the al)duminal 



