POLicnorus. 171 



beneath, with the pubescence white, the hind tibia blackish except the 

 base. Rarely, the male, with immaculate femora, has merely a blackish 

 stripe down the back of the hind tibia ; were this also effaced, Mac- 

 quart's description would apply, so far as it goes, but he does not 

 notice the rectangular vein in this case. 



Common on the surface of pools overgrown with water-plants. 

 (E. S. I.) 



38. latipennis, Fin. dol. 8. 1 (1823); Mg. ; Stn. ; Mq. ; Stg. ; 

 Ztt. Nigro-anens, fronte cyanea, hypostomate elongate argenteo, antenuh 

 capite longioribm atris, pedibux Jlavix, tarsis nigris bad Jlavis, femoribns 

 poster iorib us pluri-spinosis ; Mas. alls rotundato-dilatatis, stir/mate cos- 

 tali atro. Long. 2-^ ; alar. 4-| lin. 



Brassy-black, or olive. Front shining steel-blue. Face elongated, 

 silvery -white, in the female duller. Palpi pale silvered. Antenna 

 black, elongated, in the male much longer than the head is broad ; the 

 first and second joints of equal length, oblong, the first very hairy 

 above in the male ; the third joint shorter, especially in the female, 

 oval, the tip ascending in a point ; arista rather thick. Wings short, 

 hyaline, the bend of subapical vein obtuse-angled ; in the male very 

 broad rounded, the discal areolet long, the transverse vein distant from 

 the margin by scarcely its own length, the black costal sicelling very 

 thick. Legs and fore coxae yellow ; tarsi black ; metatarsi yellow tipped 

 with black ; fore tarsus not longer than tibia ; from three to five spines 

 on the hind femora, not so many on the middle pair. In the male the 

 fore coxae and the femora are glossed with white, and nearly denuded 

 of pubescence. 



Rare, on the sea-coasts. (E. I.) 



Obs. The number of spines on the hind metatarsus may afford 

 some specific characters, being pretty constant in eacb species, 

 except that there are sometimes more in the male than in the 

 female. Counting only those in the uppermost row, we find them 



many in Sp. 1 m., 2. 



four in Sp. 15 m., 19 m., (10, 34 m.) 



three in Sp. 1 f., 4 m., 7, 8 m., 9 m., 10 m., 11 m., 12, 15 f., 17 m., 

 20,21,28,33 m., 34. 



two in Sp. 8 f., 9 f., 10 f., 13 m., 14, 16, 17 f., 18, 22, 23, 24 m., 

 25, 26, 27 m., 31, 32 m., 33 f., 35, 37, 38 m., (1 f., 34 f.) 



one in Sp. 29, 30 m., 36. 



Obs. There are three species introduced into the British lists, 

 yet unnoticed, which may probably belong to this section, viz., 

 D. relictus, Mg., a doubtful species, unknown to Stannius, and 

 given as British without grounds ; and D. rusticus, Mg., which 

 may perhaps be the female D. atripes, as it does not seem to 

 agree with the species described by Stannius as D. rutticus, in 



