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Show 216 AUACHNlUES. The body is entirely soft in the remainder. Several species or this division live on Birds and Quadrupeds. Some are known· such as the ' Gam. telarius; .lie. telarius, Fab.; which form extremely fi · webs on th~ .l~aves of several ?la~ts, pa~ticularly of the Elm, a;~ are very inJur19us to them. fh1s particular species is reddish with a blackish spot on each side of the abdomen. 1 CHEYLETus, Lat. Didactyle chelicerre; but the pal pi arc thick, resemble a1·ms and ha vc a falciform termination(l ). ' OmnATA, Lat.-Notaspis, Herm. The chelicerre are also didactyle in the Oribatre, but their palpi are very short or concealed; their body is invested by a firm, cori· aceous or scaly skin resembling a sqield, and their legs are long or moderate. The anterior part o~ the body projects into a snout, and an appearance of a thorax IS often observable. The tarsi, in some, are terminated by a single hook, and in others by two or tluee, without any vesicular pellet. They are found on stones, trees, and in moss; their gait is slow(2). U ROPODA, Lat. Judging from analogy, we presume that the Uropodre are fur· nis~ed with f~rceps-like c~elicerre. Their palpi are not apparent; the1r body, stlll covered w1th a scaly skin, has but very short legs, and a filament at the anus, by means of which they attach them· selves to certain coleopterous Insects, suspending themselves in the air(3). found on the corp us callosum of the human brain;- T1·ombidium longipes, Herm., 1~., I, ~;-:-Jlcaruscoleoptratorum, Fab.; De Geer, Mem. Insect., VII, vi, 5;-AcariU lttrundtnlB, Berm., lb., I, 13;-Jlc. ve.Ypertilionis, lb., 14;-Trombidium bipuatula· tum,_Ib., ll, 10;-Tromb. socium, lb., II, 13;-Tromb. tiliarium, lb., 12;-Tromb. lelanum, lb., 15: these three species live in society on leaves covering them with extremely fine and silky fi.laments;-Tromb. celer, lb., 14;~Jlcarus gallinll, De Geer, Insect., VII, vi, 13. ( ~) .llcarus eru_ditus, Schrank., Enum. Insect. Aust., No. 1058, Tab. II, 1; ejusd., pec~ettlus muscult, lb., No. 1024, I, 5. (2) See Hermann, Mem. Apter., genus Notaspis; and Olivier, Encyc. Method., Insect., article Oribate. (3) .O.carua vegetans, De Geer, Insect., VII, vii, 15. The Jlcarus spinitarBW, Ilerm. Mem. Apter. VI, vi, 5, perhaps forms a genus intermediate between this and the preceding one. TRACHEARI.IE. 217 AoARus, Fab. Lat.-Sarcoptes, Lat. Two didactyle chelicerm, and very short or concealed palpi, as in the preceding; but the body very soft or without a scaly crust. The tarsi have a vesicular pellet at their extremity. Several specie. s live on the food of Man, and others are found in his psoraic ulcers, and in those of the Horse, Dog, and Cat( 1 ). Others,called Ticks-RrorNrlE, Lat.-also have eight legs, solely adapted for running, but are destitute of chelicerre, properly so . called; they are replaced, however, by two lancet-like blades, which, with the ligula, form a sucker. Sometimes they have distinct eyes, and salient, filiform, free pal pi; a sucker composed of membranous parts, and entire; and a very soft body. They are errant animals. BnELLA, Lat. Fab.-Scirus, Herm. Elongated pal pi, bent into an elbow, with setre or hairs at the extremity; four eyes; the posterior legs longest; sucker projecting in the form of a conical or subulate rostrum. Found under stones, bark of trees, and in moss. Bd.longicornis; .llcaruslongicornis, L.; La Pince rouge, Geoff.; Scirus vulgaris, Herm., Mem. Apter., III, 9; IX, S. Hardly half a line in length; scarlet; the feet paler; sucker in the form of an elongated and pointed rostrum; quadriarticulated palpi, the first and last joint of which are the longest; the latter somewhat the shortest of the two, and terminated by two setoc. Common in the environs of Paris; under stones(2). SMARIDIA, Lat. Distinguished from Bdella by the palpi, which arc hardly longer than the sucker, straight and without terminal setre; by the eight eyes, and by the two anterior legs, which are longer than the others(3). (1) Acarus domesticus, De Geer, lb., V, 1-4;-Jlcarus siro, Fah.;-.ac. scabiei, lb., 12, 13. See the disscrt. of Dr G~let;-Jlc. farinre, lb., 15 ;-Jlc. avicularum, lb., VI, 9;-.llc. passerinus, lb., 12, remarkable for the size of its third pair of legs;-.8.c. dimidiatus, Herm., Mem. Apter., VI, 4;-Trombidium expalpe, lb., IT, 8. (2) Scirus longirostris, Herm., Mem. Aptc:1·. VI, '2 ;- S. latiro.Ylris, lb., Tl, ITI;S. aetirostris, lb., III, 12; IX, T. (3) Acarus sambuci, Schrank, and perhaps the following Trombidia of Hermann; Tr. miniatum, 1, 7;-Tr. papillosum, II, 6;-'l'r. squammatum, lb., 7. The second is even closely allied to the species which serves as a type to the genus. v OL. III.-2 c |