Polydrusus.] RHYNCHOPHORA. 199 
POLYDRUSWUS, Germar. 
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 Phyllobii, 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 Polydrusus 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 tibie flattened, and fur- 
nished with two raised keels enclosing a channel 
between them; scales long and narrow. Length 
3-83 mm. (Ludipnus, Thoms.) Me aca: 
Ii. External margin of tibiee without double raised keel. 
i, Scape of antennz shorter, not reaching beyond 
the posterior margin of the eyes; upper surface 
thickly clothed with round green scales; mentum 
concealing the maxilla (Chrysoyphis, De G.) ; 
TENS TNO Ose Me vot eet el net os sy ete es 
ii. Scape of antenne longer, evidently reaching 
beyond the posterior margin of eyes; length 
4—6 mm, 
1. Femora simple. 
A. Last two or three joints of funiculus of 
antennz nearly as broad as long; scrobes 
more prolonged behind; colour greyish- 
brown, unicolorous or with grey fascie . P. TERETICOLLIS, De GQ. 
(undatus, F ) 
P. MICANS, F. 
P. sERICEUS, Schall. 
B. Last joints of funiculus of antenne 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 . 5, SORE, eo” Bmore 
b. Temples without prominences behind eyes; 
abdomen squamose ; scrobes not reaching 
anterior margin of eyes; scales dull . . P. FLAVIPES, 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. PLANIFRONS, Gyll. 
P. PTERYGOMALIS, Boh. 
