COLEOPTERA. 465 



All the Byrrhii remain on the ground in sandy localities *. 



It is impossible to describe the Clavicornes of our second section, 

 although a very natural one, but by the reunion of several characters. 

 Some of these Insects are removed from all others of the family by 

 their, antennae, which consist of nine or six joints; they are those, 

 which, in this respect, seem to approximate most closely to the Palpi- 

 cornes. The antennae of the other Clavicornes of the same section 

 are composed of eleven or ten joints ; but sometimes they are not 

 much longer than the head, and from the third joint form an almost 

 cylindrical or fusiform club, arcuated and somewhat serrated; some- 

 times they are nearly filiform and as long as the head and thorax 

 united ; but here, as in most of the other subgenera of the same divi- 

 sion, the tarsi are terminated by a large joint furnished with two 

 strong terminal hooks. Those of some — Helerocerus, Georissm — 

 consist of but four joints. 



The body of these Insects is generally ovoid, and their head 

 plunged to the eyes in a trapezoidal thorax, ^\•ith a recurved lateral 

 margin, and terminating posteriorly in acute angles ; the preester- 

 num is dilated anteriority f, and the legs are imperfectly contractile. 

 They are found in the water, under stones in the vicinity of shores, 

 and frequently in the mud : some of them — Dry ops — are allied to the 

 Gyrini by the structvire and shortness of their antennse. 



I will divide this section into two tribes J. The Insects which com- 

 pose the first or the Acanthopoda are remarkable for their flattened 

 and tolerably witle tibiae, armed anteriorly with spines ; for theii 

 short quadriarticulated tarsi, the hooks of which are of the usual size; 

 and for their depressed body. The preesternum is dilated. The an- 

 tennae are a little longer than the head, arcuated, and formed of 



* For the other species, see Fabricius, Olivier, Schoenherr, Gyllenhal, &c. 



The genus Murmidius, Leach, according to that gentleman, belongs to this tribe. 

 The antennje are composed of but ten joints, the last of -tthich forms au ovoido-glo- 

 bular club. See Lin. Trans., XIII, p. 41. 



-|- Tlie Potamophili excepted. 



X We might also divide the section in the following manner : — 



I. Antennae composed of eleven joints. 



A. Autennce clavate and very short. 



a. TibicC spinous ; tarsi quadri-articulated. 



Heterocerus. 



b. Tibise simple ; five joints in the tarsi. 



POTAMOPHILUS. DrYOPS. 



B. Antennse filiform or slightly enlarged near the end, as long as the head 

 and thorax. 



Elemis. 



II. Antennae nine or six joints. 



Macroxychus. Georissus. 

 VOL. III. H H 



