OCR Text |
Show 242 INSECTA. following orders compose the class of lnsectes of the same author. That of the Suctoria, which only com priscs the genus Pulex, from its natural relations should apparently terminat the class, but as I place those Insects which are apterous at th: beginning, this order, for the sake of regularity in the system should immediately follow that of the Parasita. ' Certain English naturalists have formed new orders, based upon the wings; I see. no necessity, however, for admitting them, that of the Streszptera excepted, the name of whichap. pears to me to be erroneous( I), and which I will call Rhip. iptera(2). In the first order or the MvniAPODA, there are more than six feet-twenty-four and upwards-arranged along the whole length of the body, on a suite of annuli, each of which bears one or two pairs, and of which the first, and in several even the second, seem to form a part of the mouth. They are ap. terous(3). In the second or the TnYSANOURA, there are six legs, and the abdomen is furnished on its sides with movable parts, in the form of false feet, or terminated by appendages fitted for leaping. In the third or the P ARASIT A, we find six legs, no wings, and no other organs of sight than ocelli ; the mouth, in a great measure, is internal, and consists of a snout containing a re· tractile sucker, or in a slit between two lips, with two hooked mandibles. In the fourth or the SucTORIA, there are six legs, but no wings( 4) ; the mouth is composed of a sucker inclosed in a cylindrical sheath, formed of two articulated portions. In the fifth or the CoLEOPTERA, there are six legs, and four wings, the two superior of which have the form of cases, and (1) Twisted wings. The parts taken for elytra are not so. See tlus order. (2) Wings folded like a fan. (3) Destitute of wings and scutellum. ( 4) They undergo metamorphoses and acquire organs of locomotion which they did not possess at first. This character is common to the following orders, but in the latter the metamorphosis developes another sort of locomotive organs-the wings. INSECTA. 243 dibles and maxillre(l) for mastication: the inferior wings maen simply folded crossw•is e, an dth e cases, always horizontal, ar • 1 . are crustaceous. They ex per1ence a comp ete metamorphosis. In the sixth or the 0RTHOPTERA(2), there are· six legs; four wings, the two superior in the form of cases, and mandibles and jaws for mastication, covered at the extremity by a galea; the inferior wings are folded in two directions, or simply in their length, and the inner margins of the cases, usually co. riaceous, are crossed. They only experience a semi-metamorphosis. In the seventh or the HEMIPTERA, there are six legs and four wings, the two superior in the form of crustaceous cases, with membranous extremities, or similar to the inferior, but larger an(l firmer; the mandibles and jaws are replaced by setre forming a sucker, enclosed in a sheath composed of one articulated, cylindrical or conical piece, in the form of a rostrum. (1) The maxilhe of coleopterous Insects, in conjunction with the mandibles, usually have this tt·iturating function assigned to them. M. Hentz, P clistinguished American entomologist, Trans. Phil. Soc., III, part ii, p. 4."'S, is of the opinion that in many cases the maxilla: must be considered as :-.,ere appendages to the tongue, and that their office is to assist in deglutition, seldom serving to gt·ind or lAcerate, except in the Melolontlddre, Rtttelirlm, and some others, where there seems to be a departure from the it• primary use. In corroboration of this idea lte adduces the configuration of the maxilla: of several Insects, in which he has been fortunate enough to detect a retractile appendage hitherto unknown. The first is the Cantharis marginata, Fab., whose maxilla:, when dried, offer but one bifid lobe; if, however, the abdomen and thorax of the recent animal be gradually compressed, a soft, clastic, sub-conic body is protruded from the cleft of that lobe, more than halfits length, and extending beyond the palpi; a second appendage of the same kind, and about half its length, projects at right angles from the base of the first, which is directed forwards: both arc covered with hairs. The second is the Canth. bimaculata, }'ab., in which this appendage is still more sensibly and easily display· ed, protruding by pressure from each maxilla in the form of a tapering filament covered with fine hairs, susceptible of considerable extension, reaching bcy.ond the middle of the antennre, and consequently more th!ln double the length of the maxilla itself. I have verified these facts in this last species. The use of these organs in collecting nourishment from flowers is evident. See Trans. Phil. Soc. ut sup. pl. XV, f. i, e, and f. ii, e. Jlm. Ed. (2) De Geer established this order under the name of Dermaptera, improperly chan~ed by Olivier to that of Ortlwptera. We preserve the latter, however, as na· turahsts have generally adopted it. |