COLEOPTERA. 521 



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

 duced beliind into a loiii^er or shorter acute spine ; the maxillary palpi are longer than the antennie ; the taisi, 

 especially of the hind le^s, have a long row of fringes, and are terminated by sniall ungues of uutqual 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, Jl. picciis, 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 tlies well, but walks badly ; its sternal point is capable of intlicting a severe wound. The anus of the 

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

 like a curved lioi'n ; its outer surface is coated with ^um, which renders it impei'vious 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 exti'emity of the body, are 

 very voracious, and feed on the young fry in tish-ponds. That of U. piccm is depressed, blackish, wrinkled, wiih 

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

 sei/.e 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 respiratirm. Other larv;c of Mydrophili are destitute of these 

 api)endages, and are not able to swim, and do not suspend themselves in tlie same manner as the preceding. The 

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

 these species belong to the extreme genera. 



//^/(froy}//(7»,y 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. [Hydrophihis 

 Vi ''" If^/^ W'' caraboldes, a most abundant British species, of an olive-black colour.] 

 >;/ \r In the three following subgenera the middle joints of the club of the antennae are not dilated 



and prolonged in front into a spine. 



Lininehius, Leach, has the maxillary palpi much lunger than the aiitennte ; the lar:it joint 

 shorter than the preceding, and cylindrical, and tiie tip of the elytra truncate. //. gr'iscus, 

 iniiicateiliis, &c. 



ITydrohius, 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. scarabu:- 

 oidesy mdanocephahis, &c. 



carauijiues. iit'nj-i-H.s, Lcach, diflers 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. 

 Hydr. liiridus, Fab. 



The second tribe, Sphceridiota, 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, Avith the presternum prolonged into a 

 point at its posterior extremity, and the tibi?e spinose, the anterinr being palmatcd or digitated in the 

 larger species. Tlie antenna: have always nine joints, or simply eight, if the last is considered as an 

 appendage of the preceding. (Sec 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 tlie 

 margins of water. They compose the genus 



Si*H--r.RiDiuM, Fabr. 



Sphceridiiim proper, of Leach, comprises only tho^e species which have the anterior tarsi of Llie 

 males dilated. Dennestes scarabceoides, 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 antenme loosely imbri- 

 caled, form the genus ICercyon, not] Cerajdion of Leach; Sph. uiupuncta/.mn, Linn. Tlie form of 

 the tibiae and the arrangement of the spines or teeth would enable us to divide Sphsridium into 

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

 niucli multiplied. 



TIIE SIXTH FAMILY OF TIIE COLEOPTERA PENTA]\IERA,~ 

 The Lamellicornes, — 



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 

 turee joints, which are lamellar; sometimes arranged like a fan, or the leaves of a book, o])ening and 



