OCR Text |
Show 336 INSECTA. FAMILY III . . SERRICORNES. In the third family( I) of pentamerous Coleoptera, as in the preceding and following families of the sa.me order, we find but four paJpi. The elytra cover th~ abdomen, which, witn some other characters, distinguish the Insects which compose it from the Brachelytra just mentioned. The antennre, with some exceptions, are equal throughout, or smaller at the ex· tremity, dentated, either like a saw or a comb, or even like a fan, and in this respect are most developed in the males. The penultimate joint of the tarsi is frequently bilobate or bifid. These characters are rarely found in the foJlowing family, that of the Clavicornes, to which we arrive by such insensi. ble gradations, that to define its limits rigorously becomes a very difficult matter. Some, in which the body is always firm and solid, and most commonly oval or elliptical, with partly contractile legs, have the head plunged verticaliy into the thorax up to the eyes; and the prresternum, or median portion of that· thorax, elon. gated, dilated or reaching to beneath the mouth, usually distin· guished on each by a groove in which the antennro-always short-are lodged, and prolonged posteriorly into a point, which is received into a depression of the anterior extremity of (1) The Silplue are the only pentamerous Coleoptera in which, as in the pre. ceding ones, we find an excrementitious apparatus; but it is not binary as in the !at· ter, and the exterior canal opens directly into the rectum, like the urethra ofllirds. From these considerations then it would seem that the Silpba:, as well as other Clavicornes, should come directly after the Brachelytra. Other considerations had led me to a similar approximation.-See pref.<tce to my Consid. Gen~r. sur l'Ordrt Nat. des Crust., &c.-According toM. Leon Dufour, who has furnished me with these anatomical remarks, the hepatic ducts of the Bupt·estides and Enterides, or of my Sternoxi, in number, length, and mode of insertion, resemble those of the Carabici. The Lampyrides and Melyrides, also, have but two hepatic vessels, b~t there are four in Telephorus, Lycus, and Ptinus. Of all the Insects of this (Sern· corne) family, whose organization he has investigated, he finds the longest alimen· tl4ry canal in Malachi us, Drilus, and Anobium. COLEOPTERA. 337 the mesosternum. These anterior legs are at a distance from the anterior extremity of the thorax. They form our first section or tlJUt of the STERNOXI. Others, whose head is enclosed posteriorly by the thorax, or at ]east covered by it at base, but in which the prrosternum is not dilated, and docs not project anteriorly in the manner of a chin-c1oth, nor is usually( I) terminated posteriorly iu a point received into a cavity in the mesosternum, and in which the body is most commonly either entirely or partially soft and flexible, constitute our second section, that of the MALACODERMI. A third and last, that of the XYLOTROGI, will comprise those Serricorncs, in which the posterior extremity of the prresternum is not similarly prolonged, but whose head is completely exposed and separated from the thorax by a strangulation or species of neck. We will divide the 8ternoxi into two tribes. In the first or that of the BuPRESTIDEs, the posterior projection of the prresternum is flattened, and not terminated in a laterally compressed point, that is simply received into a dept·ession or emargination of the mesosternum. The mandibles ft·equently terminate in an entire point, without any fissure or emargination. The posterior angles of the thorax are either but very slightly or not at ali prolonged. The last joint of the palpi is most commonly nearly cylindrical, hardly thicker than the preceding ; the others are globular or ovoid. Most of the tarsial segments are generally wide or dilated, and furnished beneath with pellets. These Insects never leap, a character which eminently distinguishes them from those of the following tribe(2): they compose the genus (1) The Cebriones are an exception, and approximate, in this respect, to the Elaterides; but the inferior extremity of the pra:sternum does not advance undet• the head. The mandibles project, are ar~;:uat~d and simple; the pnlpi filiform; the legs non-retractile, and the two ante:-ibr"' ones somewhat removed, at base, from the anterior extremity of the thorax, and closely approximated. (2) The Insects of this tribe also differ from all others of the family in their trache;e which are vesicular-in the J'est they are tubulat·. See Obs. Anatom., of M. Leon Dufour. VoL III.-2 S |