COLEOPTERA. 521 



saucer-shaped, more elongated on the front side ; the sternum is elevated in the middle into a keel, which is pro- 

 duced behind into a longer or shorter acute spine ; the maxillary palpi are longer than the antennae; the tarsi, 

 especially of the hind legs, have a. long row of fringes, and are terminated by small ungues of unequal size. 

 In some the sternal spine is very much elongated behind, and the last joint of the anterior male tarsi is triangu- 

 larly dilated. These are the Hydrous of Leach ; one of which, 11. picetu, Fab., is an inch and a half long, oval, 

 and of a black brown colour and highly polished. [It is a common British species, frequenting ponds and ditches] ; 

 it swims and flies well, but walks badly ; its sternal point is capable of inflicting a severe wound. The anus of the 

 female is furnished with two spinnerets, with which it constructs an ovoid cocoon of silk, surmounted by a point 

 like a curved horn ; its outer surface is coated with gum, which renders it impervious to the water; and in its 

 interior the eggs are symmetrically arranged. These cocoons float on the surface of the water. 



The larvae resemble worms, being soft and of an elongated conical form, with six feet ; the head large and scaly, 

 more convex below than above, and armed with strong mandibles ; they respire by the extremity of the body, are 

 very voracious, and feed on the young fry in fish-ponds. That of II. piceus is depressed, blackish, wrinkled, with 

 the head reddish brown, round, and capable of being thrown back upon the back; by which means it is able to 

 seize small shells floating on the surface of the water, its back serving it as a point d'appui for breaking the snail 

 shell. They swim well, and have two fleshy appendages at the extremity of the body, used in enabling the insects 

 to suspend themselves at the surface while in the act of respiration. Other larva; of Hydrophili are destitute of these 

 appendages, and are not able to swim, and do not suspend themselves in the same manner as the preceding. The 

 females of these species swim with difficulty, and carry their eggs beneath the abdomen in a silken tissue ; but 

 these species belong to the extreme genera. 



Hydrophilus proper, of Leach, consists of species having the tarsi alike in both sexes and 



not dilated, with the sternal spine not extending beyond the metasternum. [llydrophilus 



caraboides, a most abundant British species, of an olive-black colour.] 



In the three following subgenera the middle joints of the club of the antennae are not dilated 



and prolonged in front into a spine. 

 Limnebiut, Leach, has the maxillary palpi much longer than the antennae; the last joint 



shorter than the preceding, and cylindrical, and the tip of the elytra truncate. //. griseus, 



truncatellus, &c. 

 Hydrobius, Leach, has the maxillary palpi scarcely longer than the antenna?; the body 



convex; the eyes depressed, and the front of the head not suddenly narrowed. H. tcarabte- 

 Fig. 67.— Hvdrophilus oidcs, melanocephalus, &<•. 



Berosus, Leach, difl'ers from the last in having the eyes very prominent ; the front of the 

 head suddenly narrowed, and the thorax narrower at the base than the elytra ; the body is very gibbose. 

 llydr. luridus, Fab. 



The second tribe, Spharidiota, is formed of terrestrial Palpicornes, with the tarsi composed of five 

 distinct joints, the basal joint being at least as long as the second. The maxillary palpi are rather 

 shorter than the antennae. The body is nearly hemispherical, with the prosternum prolonged into a 

 point at its posterior extremity, and the tibiae spinose, the anterior being palmated or digitated in the 

 larger species. The antennae have always nine joints, or simply eight, if the last is considered as an 

 appendage of the preceding. (See the Elaterides, and some other genera of Coleoptera.) These insects 

 are small, and inhabit cow-dung and other excrementitial matter, and some species are found near the 

 margins of water. They compose the genus 



SpH.iiiumuM, Fabr. 



Sphceridium proper, of Leach, comprises only those species which have the anterior tarsi of the 

 males dilated. Dermestes scarabaeoides, Linn., is shining black, smooth, with very spiny feet, a spot 

 of blood-red at the base of each elytron, and the tip reddish. These spots vary, and even disappear in 

 some specimens [of this very common British insect]. 



The species which have the tarsi alike in the two sexes, with the mass of the antenna; loosely imbri- 

 cated, form the genus [Ccrcyon, not] Cercydion of Leach; Sph. uniptmctatum, I. inn. The form "f 

 the tibiae and the arrangement of the spines or teetli would enable us to divide Sphseridiom into 

 several other groups, which would facilitate the study of the species, which have probably been too 

 much multiplied. 



THE SIXTH FAMILY OF THE COLEOPTLKA I'KNTAMF.RA,— 



THE L \mi:i t EC0HNK8, — 



lias the antenna' inserted in a deep impression beneath the lateral margins of the head, always short, 



mostly composed of nine or ten joints, and terminated in all by a mass generally formed of the last 

 three joints, which arc lamellar; sometimes arranged like a fan, or the leaves of a 1 k. opening and 



