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Show 372 iNSECTA. in the thorax, and the maxillary palpi are never at the same time so much projected and clavate; the ensemble of their physiognomy also exhibits other differences. The genus Rister forms our second tribe, which, with baron Paykull, who has so profoundly studied it, we will name the HlsTEROIDES. Here the fotir posterior legs are more remote from each other at hase than the two anterior, a character alone that distinguishes this tribe from all others of the same family. The legs are contractile, and the outer side of the tibire is dentated or spinous. The antennre are alwaysge· niculate, and terminated by a solid club composed of crowded joints. The body is extremely firm, and usually forms a square or parallelopiped; the prresternum is frequently dilated ante· riorly, and the elytra are as often truncated. The mandibles project, are strong, and frequently unequal as to size. The palpi are almost filiform, or slightly enlarged near the end, and terminated by an oval or ovoid joint. In habits, the de~tations of their tibire, and some other characters, these Insects seem to approach the Copropha~ Lamellicornes, but from other considerations, founded on their anatomy, they approximate to the Silphre-such also is the opinion of M. Dufour, Ann. des Sc. Nat., Octo b. 1824. The alimentary canal of the species he dissected-the sinuatusis from four to five times the length of the body. The reso· phagus is very short; the oblong enlargement that imme· diately follows exhibits through its parietes certain brown~h lines, which seem to indicate the existence of internal tritu· rating appendages; if this be the case, the enlargement is en· titled to the appellation of gizzard; the chylific ventricle is very long, flexed, and studded with pointed and very salient papillre. The hepatic vessels have six distinct insertions round the chylific ventricle-Ibid. July 1825. Randohr reduces their number to three, so that each of them would have two insertions : but such a disposition of their vessels is doubtful. has detected the S. clavatus, Gyll., in an Ant-hill near Paris. This.fact, with some .others, confirms me in my opinion that these Insects, with the Pselnphii, imme· diately follow the llrachelytra. COLJWPTERA. 373 These animals feed on cadaverous or stercoraceous matters and decomposing vegetable substances, such as dung, old mushroo~m:, &c.: some establish their domicil under the bark of trees. Their gait is slow, and their colour a brilliant black or bronze. Such of their larvre as have been observed-those of the merdarius, carlaverinus-feed on the same substances as the perfect Insect. Their body is glabrous, soft, and of a yellowish white, the head 'and first segment excepted, the dermis of which is brown or reddish; it is provided with six short legs, and is terminated postet·iorly by t\vo articulated appendages, and an anal and tubular prolongation; th~ squamous plate of the first segment is longitudinally eanaliculated. This tribe, as we have already stated, will consist · exclusively of the genus RisTER, Lin. Baron Paykull restricted his division of this genus to the separation of certain strongly flattened species, with which he formed that of Hololepta, but Doctor Leach has established four more(l). In some, the tibire, at least the anterior ones, are triangular, dentated exteriorly, and the antenm:e always free and exposed; the body is generally square, but slightly or not at all inflated. fhey may be divided into two subgenera. In the first or HoLOLEPTA, Payk. The body is strongly flattened, the prresternum does not project over the mouth, and the four posterior tibire have but a single range of spines; the terminal lobe of the maxillre is prolonged; the mentum, is deeply emarginated, and the palpi, proportionally more advanced, are formed of almost cylindrical joints. They live under the bark of trees. The animal figured by Paykull, as the larva of a species of this subgenus, is that of a species of Syrphus, or Fly(2). The other Histeroides, in which the prresternum projects over the mouth, the maxillre are terminated by a short lobe, with but slightly projecting palpi composed of joints which, the last excepted, are (1) Zoo]. Miscell., III, p. 76. (2) liist. Monog., p. 101, et seq . |