Ba yoina. | RHYNCHOPHORA. 285 
truncate or emarginate at apex, but not (or very rarely, and then not 
strongly) bilobed ; the lobes at the sides of the thorax are distinct and 
often partially cover the eyes, which are round; the posterior cox are 
very broadly distant; the scutellum is small; the elytra have the 
shoulders well marked and are usually bluntly produced at apex; the 
femora are simple; the prosternum is broad before the anterior cox 
and is emarginate at apex ; the surface of the body is usually furnished 
with a hydrofuge tegument, or in simpler language a covering which 
repels water ; three genera have been regarded as British—Hydronomus, 
Bagous and Lyprus ; the latter of these has for some time been united 
with Bagous, and Bedel appears to be right in also regarding Hydro- 
nomus asa portion of Bagous, as the differences scarcely appear to be 
generic. 
BAGOWUS, Schinherr (Hydronomus, Schénherr). 
About fifty species have been described as belonging to this genus, 
but as no less than thirty-twc have been found in Europe, and it is 
known that representatives occur throughout Northern Asia and North 
America, it is probable that the number will be very largely increased ; 
species have also been described from Algeria, South Africa, Cuba, &c.; 
they are so extremely sluggish and retiring in their habits, which are 
altogether subaquatic, that they are very seldom met with, so that 
although no less than fourteen or fifteen species have been recorded as 
British, they are, with few exceptions, scarcely represented in any 
collections, and in list after list of localities the genus is returned as 
almost entirely blank; they are, however, gregarious, and in the 
localities in which they occur, several of the species have been taken 
by collectors who have found out their habits, in large numbers ; the 
chief characters of the genus have been mentioned above ; in form and 
general appearance the species greatly resemble one another, and they 
are in many cases difficult to determine except by comparison with 
authentic specimens. 
The larva of B. (Hydronomus) alismatis has been observed by Kaltenbach; it is 
found feeding on the leaves of Alisma plantago and undergoes its transformations in 
the part of the plant where the base of the leaf like a sheath enfolds the stem of the 
plant ; the perfect insect appears at the beginning of the summer, 
The British species may be roughly distinguished as follows, but the 
characters, in several cases, are not very satisfactory. 
I. Prosternum flat before the anterior cox; antenne 
with the first joint of the funiculus longer than 
the second (Hydronomus, Schénh.) panes 
II. Prosternum with an excavation before the an- 
terior coxe, which is margined on each side; 
antenne with the first joint of the funiculus about 
equal to the second ( Bagous, i. sp.). 
i. Club of antennz with the first joint glabrous 
and as long as all the following joints united ; 
B. ALISMATIS, Marsh, 
