Genera Bledius, Heterocerus^ and Dyschirius. 37 



labrum is long, hard, rounded in front, the edge shghtly emar- 

 ginate in the middle, with four strong, short, thick and blunt 

 spines on each side. The maxilla3 and labium are elongated and 

 narrow ; the palpifer of the maxillse 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 antennae 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 coxre are transverse ; the trochanters 

 support the femora, which are spindle-shaped; the tibia? 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. 

 It 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 



