ARACHNOIDEA. 579 



Sp. Dermanyssus avium DUG s, GERV., (Smaridie des petits oiseaux) DUMERIL 

 Cons. gen. s. I. Ins. PL 52, fig. i, LYONET Eeckerch. PL 5, fig. n, DUGES 

 Ann. des Sc. not. 2e SeVie, Zool. Tom. n. PI. 7, fig. i ; DUGES and KOCH 

 unite with this species the Acarus Gallince DE GEER Mem. vu. PL 6, figs. 

 13, 14, and Acarus hirundinis HERMANN, PL i, fig. 13. This species lives 

 in bird-cages and hen-houses, and sucks the blood of the animals, especially 

 by night. Other species live on different birds, on bats, &c. 



Gamasus LATE, (with the addition of genera Siro and Macro* 

 keles ejusd.). Mandibles chelate, denticulate. Labium trind. Body 

 dth dorsal shield coriaceous, mostly double. Anterior feet mostly 

 mger ; second pair of feet in some incrassated. 



Sp. Gamasus coleoptratorum, Acarus coleoptratorum L., R(ESEL Ins. iv. Tab. 

 i, figs. 10 13, DE GEER Mem. vu. PL 6, fig. 15, KOCH in HERRICH- 

 SCH.EFFER Deutschl. Ins. Heft 168, Tab. 19 ; the beetle-mite : the body has 

 an orange-yellow or blood-red colour ; many insects, that creep under- 

 ground, or live in dung, especially beetles (Geotrupes vernalis, stercorarius) 

 have sometimes their entire body covered with hundreds of these mites. 



This numerous genus contains moreover many species that live on the 

 ground, in mosses, underwood, and moist pastures. Also the mite which 

 was met with by LYONET on the caterpillar of Cossus ligniperda belongs 

 here. Heck. PL 6, figs, n, 12. 



Sub-genus : Lcelaps, Zercon, Sejus KOCH. 



Consult Ueberslcht des Aracknidensystems, 3tes Heft, 30 Abtheil. 1843. 



Family VII. Hydrarachnidia. Palps with last joint unguicu- 

 ite or spinose. Eyes two or four, distinct. Feet with broad coxae, 

 lostly ciliated, natatory, posterior surpassing the rest in length. 

 Aquatic animals. 



Compare ffydrachnce, quas in aquis Danice paluslribus detexit, descripsit, 

 pinyi et tdbulis xi. ceneis incudi curavit O. F. MUELLER, Lipsise, 1781, 4to. 



The distinction of these water-spiders as a peculiar genus is to be ascribed 

 to O. F. MUELLER. LINNAEUS had not received these animals into his 

 Systema naturce ; FABRICIUS in his Entomologia systematica, united the 

 species then known to him with his genus Trombidium, and only after- 

 wards, in his Systema antliatorum, made room for a distinct genus for these 

 species under the name of Atax, p. 366. Besides the genus Hydrachna of 

 MUELLER we also receive into this family a species of Acarus of LINN.EUS, 

 which is the typus of the genus Limnockares of LATREILLE. 



Limnochares LATR. Palps scarcely longer than rostrum. Eos- 

 rum conical, truncated ; mandibles indistinct, with last joint subu- 

 ite. Ocelli four. Legs pilose, four posterior remote. 



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