THE GROUP OF SALICl'S, PAVIDUS, AND ALBIPENNIS. 161 



the costa, stigma, and nervures (except at the apex), yellow. The first 

 transverse cubital nervure is very faint ; the second cubital cellule IB 

 about a quarter longer than the third ; the second recurrent nervure 

 is nearly joined to the second transverse cubital. 



The <$ is unknown. 



Length 3 lines. 



Ab. a. Stigma black at the base. 



I. Dorsal surface of abdomen without black. 

 c. Wings (especially posterior) smoky. 



From the other British species of this section N. 

 acuminatus differs in its narrow, sharply pointed face ; 

 in the abdomen being narrowed towards the base, and 

 especially towards the apex; also in the deeper 

 notched clypeus, which is quite white, in the black 

 dorsal stripe on the abdomen, distinctly white tibia3, 

 long spurs, and the yellowish alar nervures. 



N. acuminatus has occurred in Clydesdale, Rannoch, 

 Kingussie, Srathglass, Braemar, and Sutherlandshire, 

 and is tolerably common. The larva feeds on birch, 

 and resembles closely that of N. dorsatus, unless I have 

 made some mistake through having at the time con- 

 founded acuminatus with dorsatus. 



Continental distribution : Lapland, Sweden, Ger- 

 many, France. 



XVIII. THE GROUP OF SALICIS, PAVIDUS, AND 

 ALBIPENNIS. 



Yellow species which have the head above the clypeus 

 black 9 more or less broadly bordered with yellow round 

 the eyes, the pleura? and breast entirely black, or both 

 may be yellow a.s in salicis, or the pleurce only yellow as 

 in bipartitus ; the mesonotum always bears some black , 

 and the abdomen may be marked with black at the base 

 or may be entirely yellow. Stigma rarely black, or 

 fuscous, often yellowish. Clypeus incised. Antennae 



VOL. II. // . 11 



