466 INSECTA. 



eleven joints, the last six constituting an almost cylindrical and 

 slightly serrated club ; the second is short and not dilated. 

 This tribe is composed of a single genus 



HETEROCERUS, Bosc., Fab. 



These Insects are found in the sand or mud, along the borders of 

 rivulets, marshes, &c., issuing from their holes when disturbed by the 

 trampling of feet. The form of their tibiae enables them to turn up 

 the earth, and conceal themselves in it ; their tarsi can be flexed upon 

 the tibiae. There also reside their larvae, which were first discovered 

 by M. Miger. 



H. marginatus, Fab.; H. Icevigatus, Ib.; Panz., Faun., Insect., 



Germ., XXIII, 12. A small, blackish, and silky Insect, with 



little yellowish or reddish spots, varying in form and number, 



and sometimes even wanting on the elytra. 



M. Gyllenhal observes that the tarsi really consist of five 



joints, the first of which is small and oblique. See Insect. Suec. 



I, p. 138. 



The second tribe, or that of the MACRODACTYLA, comprises Clavi- 

 cornes with simple, narrow tibiae and long tarsi, all one genus ex- 

 cepted (Georissus), well distinguished from every other tribe, by its 

 antennae of nine joints, of which the three last form an almost solid 

 club composed of five distinct joints, the last of which is large, with 

 two stout terminal hooks. The body is thick or convex. The tho- 

 rax is less rounded, and most commonly terminates on both sides in 

 acute angles. 



The principal type of this tribe is the genus 



DRYOPS, Oliv.y 



Or that of Parnus, Fab., which is divided in the following manner : 

 1. Those whose antennae, never much longer than the head, are 

 composed of from ten to eleven joints, which, from the third, form an 

 almost cylindrical or slightly fusiform club, arcuated, and somewhat 

 serrated. 



POTAMOPHILUS, Germ. PARNUS, Fab. 



The Potamophili, which, ignorant of the establishment of this sub- 

 genus* we had named HYDERA *, have their antennae exposed, and 

 not received into particular cavities ; they are rather longer than the 

 head ; the first joint is almost as long as the following ones taken to- 

 gether, and the second short and globular. The palpi are salient, 

 and the mouth is completely exposed as the prsesternum does not 

 project over it, a character in this tribe exclusively peculiar to this 

 subgenus f. 



* Regn. Anim., Ill, p. 268. 



t Parnus acuminatus, Fab.; Panz., Faun, Insect. Germ., VI, 8 ; Dryops picipes, 

 Oliv., Ill, 41, 1, 2. 



