Genera Bledius, Heterocerus, and Dyschirius. 37 
labrum is long, hard, rounded in front, the edge slightly emar- 
* gimate in the middle, with four strong, short, thick and blunt 
spines on each side. The maxille and labium are elongated and 
narrow ; the palpifer of the maxille reaches beyond the root of 
the palpi, forming a protruding point; the maxillary lobes are 
hard; the anterior angles of the mentum very salient; the 
lingua is cordate, hard, and spinulous; the stipites of the labial 
palpi very small, and coalesced with one another as well as with 
the lingua. The basal joint of the antenne can be laid into a 
groove in front of the eye; the club is serrated, arched, calcu- 
lated for being coiled round the eye. Prothorax narrowed 
behind, its sides extended so as to form an angle on each 
side (hitherto erroneously described as the hind corner) ; the 
prosternum possesses a short procursus labialis. The legs 
are constructed for digging, all three pairs of about the same 
size and shape; the coxe are transverse; the trochanters 
support the femora, which are spindle-shaped ; the tibiz broad, 
with a comb of spines; the spurs long and curved ; the feet 
thin, long-haired, four-jointed, the claws very thin. The body 
is in general cylindrical, rather flat or vaulted, oblong, with 
parallel or round sides. The hairy covering double, consisting 
of an inner coat to which the air clings, and an outer coat of 
longer bristles standing out from the body; both layers vary 
according to the closeness and moisture of the soil in which the 
animal has its home, being finer and closer in those which live 
in clay, coarser and stiffer in those which dig in sand, those 
which live in mixed soil presenting intermediate modifications. 
These short observations may suffice as an introduction to the 
following synopsis of Danish species; but there is one rather 
remarkable point in the structure of these Coleoptera which de- 
serves more special attention. 
_ Erichson pointed out (Naturg. d. Ins. Deutschl. iii. 539) the 
existence of a peculiar arched ridge on each side of the first 
(externally visible) ventral segment, and a similar straight and 
sharp ridge on the inner side of the third pair of femora, which 
_ he interpreted as constituting an organ of sound, as indeed it is. 
Tt seems, however, that in suggesting this interpretation, Erich- 
son was led rather by a happy instinct than by a careful exa- 
mination of these parts; for he does not give any account of 
those peculiarities of structure which really enable the animal to 
make a sound by means of this apparatus; and those parts to 
which he draws attention have in fact nothing at all to do 
with the production of the creaking sound. He says that in 
some species, the lateral part of the arched ridge is distinctly 
transversely grooved in both sexes or only in the males*, whilst 
* Referring to the descriptions of the species, we find that the lateral 
