Polydrusus.'] RHTNCUOPHORA. 199 



POX.YDRT7SUS, Gcrmar. 



The members of this genus may be known by having the scrobes 

 deep and well marked in front and angularly deflexed behind ; the 

 rostrum is short and emarginate at apex ; the vertex of the head is large 

 and the eyes are round and usually prominent ; as a rule the femora are 

 without teeth, but this is not always the case ; the species, in many 

 cases, resemble very closely certain of the PhyUobii, from which the 

 formation of the scrobes will at once separate them ; the last ventral 

 segment is rather short and variously modified in the males ; in the 

 females it is usually triangular and simple ; the genus comprises upwards 

 of a hundred species which are mostly found in the Palearctic region 

 and also in North America ; one or two species appear to have been 

 described from South America (Columbia and Brazil) ; about sixty 

 species are found in -Europe, of which only nine occur in Britain ; in 

 both the genera Polydrufus and Phyllobius many of the species are 

 covered with very brilliant golden green scales and their elytra form 

 most beautiful objects for the microscope. 



I. External margin of all the tibiae flattened, and fur- 

 nished with two raised keels enclosing a channel 

 between them ; scales long and narrow. Length 



65-85 mm. (Eudipnut, Thorns.) P. MICAXS, F. 



II. External margin of tibiae without double raised keel. 



i. Scape of antennae shorter, not reaching beyond 



the posterior margin of the eyes; upper surface 



thickly clothed with round green scales ; uientum 



concealing the maxillae (Chrysoyphis, De G.) ; 



length 5-6 mm P. SEBICEUS, ScAall. 



ii. Srape of antennae longer, evidently reaching 



beyond the posterior margin of eyes ; length 



4-6 mm. 



1. Femora simple. 



A. Last two or three joints of funicalns of 

 antennae nearly as broad as long ; scrobes 

 more prolonged behind ; colour greyish- 



brown, unicolorous or with grey fasciae . P. TEBETICOLLIS, De Q. 



(undatus, F ) 



B. Last joints of funiculus of antennae ob- 

 long, obconical ; scrobes less prolonged 

 behind ; colour brighter or duller golden 

 green. 



a. Temples raised into a prominence behind 

 each eye ; abdomen chiefly pilose ; scrobes 

 reaching anterior margin of eyes ; scales 



shining P. PTERYGOMALIS, Boh. 



b. Temples without prominences behind eyes; 

 abdomen squamose ; scrobes not reaching 



anterior margin of eyes ; scales dull . . P. FLAYIPES, De G. 



2. Femora with a larger or smaller tooth on 



their inferior margin. 



A. Thorax and elytra of a uniform colour, 

 closely covered with small round bright 

 green scales ; legs dark with green scales P. PLAXIFRONS, Gyll. 



