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Show 256 INSEC:r A. These Insects run with great velocity; some of them by m • eans of their caudal appendages are enabled to leap. They a1·e divided in two subgenera. to MAoHius, Lat.-Petrobius, Leach. Eyes very compound, almost contiguous, and occupying the greater part of the head; body convex and arcuated above· abdome . . ' n termi. nated by small threads for saltatiOn, of which the middle one . ' P1 a ced above the two others, Is much the longest. The maxillary palpi are very lat·ge, and have the fot•m of I feet. The thorax is strangulated, the first segment smaller tha:~~l second and arched. t These Insects leap well and frequent stony and enclosed 1 All the species known belong to Europe( 1 ). Paces. LEPISMA, Lin.-Forbicina, Geoff., Leach. Eyes very small, widely separated, and composed of a small num. ber of granul~s; body flattened, and terminated by three threads of equall~ngth, mserted on the same line, and of no use in leaping . . Theu· coxre are very lat·ge. Most of the species inhabit the inte· rior of houses. L. sacc,h arina; Forbicine plate, Geoff. ' Insect. , II , xx, 3• Schc:eff., Elem. Entom., lxxv .. Four lines in length; of a silver; and so mew ~at leaden hue and Immaculate; originally, it is said, from ~merica, now very common in houses in Europe. L. vtttata, Fab. Body cinereous, dotted with blackish; four streaks of the same colour along the back of the abdomen. Other species are found under stones. FAMILY II. PODURELL£, Lat. Antennre q~adriarticulated ; no distinct or salient pal pi; abdomen termmated by a forked tail folded undet• the venter when at rest, and used for leaping. The Podurellre form but one genus in the Linnrean system. (1} Lepisma polypoda, L.; L. aaccharina, Vill., Entom. Lin. IV xi I; Uoem. Gener. Insect. XXIX I· }o b" 0 z· d • • . , ' I p . : . ' • r 'ctne cy tn rtqtle, Geoff. ;-Lepwna thtzeana, Fab.;- ttrobuu marttzmuB, Leach, Zool. 1\liscell., CXLV. THYSANOURA. 257 PoDURA, Lin. These Insects are very small, soft and elongated, with an oval bead and two eyes, each composed of eight granules. Th.eir legs hlVC but four distinct joints. The tail is soft, flexible, and formed ofan inferior piece, movable at base, to the extremity of which are articulated two appendages susceptible of being approximated, separated, or crossed-they are the teeth of the fork. They have the faculty of elevating their tail, and then forcing it suddenly against the plane of position, as if they let go a spring, thus raising themselves into the air, and even leaping like the Pulices but to a less height. They usually fall on their back, with their tail extended posteriorly. The middle of the venter exhibits a raised oval portion divided by a slit. Some keep on trees and plants, under old pieces of bark, or stones; others on the surface of stagnant waters, and sometimes on that of snow during a thaw. Several unite in numerous societies on the ground, and at a distance resemble little heaps of gunpowder. Some species appear to propagate in winter. PoounA, Lat. Antennre equal, and without annuli or little joints to the last segment; body nearly linear or cylindrical; trunk distinctly articulated; abdomen narrow and oblong( 1 ). SMYNTHURus, Lat. Antennre slenderer near the extremity, and terminated by an annulated piece, or composed of little joints; trunk and abdomen united in a globular or oval mass(2). (I) Podura arborea, L.; De Geer, Insect. VIJ, ii, 1-7;-P. nivalis, L.; De Geer, lb., 8-10;-P. aquatica, L.; De Geer, lb., ii, 17;-P. plumbea, L.; De Geer, lb., iii, 1--4;-P. amln~lans, L.; De Geer, lb., 5-6;-P. aquatica grisea, De Geer, lb., ii, 18, 21. The Pod. vaga, villosa, cincta, annulata, pusilla, lignorum, .fimetaria, Fa b. (2) Podura atm, L.; De Geet•, lb., iii, 7-14; the Pod. viridi8, polypoda, minuta, and 8ignata, Fab. Vo1 .. III.-2 H |
