ARACHNOIDEA. 579 
Sp. Dermanyssus avium Due 8, GERV., (Smaridie des petits oiseaux) DUMERIL 
Cons. gén. s. l. Ins. Pl. 52, fig. 1, Lyonut Recherch. Pl. 5, fig. 11, Ducks 
Ann. des Sc. nat. 2e Série, Zool. Tom. 11. Pl. 7, fig. 1 ; Ducks and Kocu 
unite with this species the Acarus Galline Dr GrER Mém. vit. Pl. 6, figs. 
13, 14, and Acarus hirundinis HurManyn, Pl. 1, fig. 13. This species lives 
in bird-cages and hen-houses, und sucks the blood of the animals, especially 
by night. Other species live on different birds, on bats, &c. 
Gamasus LATR. (with the addition of genera Sto and Macro- 
cheles ejusd.). Mandibles chelate, denticulate. Labium trifid. Body 
with dorsal shield coriaceous, mostly double. Anterior feet mostly 
longer; second pair of feet in some incrassated. 
Sp. Gamasus coleoptratorum, Acarus coleoptratorum L., Raseu Ins. tv. Tab. 
I, figs. to—13, DE GrER Mém. vir. Pl. 6, fig. 15, Koon in Herricu- 
ScHo#ZFFeR 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. Reeh. Pl. 6, figs. 115-12. 
Sub-genus: Lelaps, Zercon, Sejus Kocu. 
Consult Vebersicht des Arachnidensystems, 3tes Heft, 3e Abtheil. 1843. 
Family VII. Hydrarachnidia. Palps with last jot unguicu- 
late or spinose. Eyes two or four, distinct. Feet with broad coxe, 
mostly ciliated, natatory, posterior surpassing the rest in length. 
Aquatic animals. 
Compare Hydrachne, quas in aquis Danie palustribus detexit, descripsit, 
pingi et tabulis x1. eneis incudi curavit O. F. Munuumr, Lipsie, 1781, 4to. 
The distinction of these water-spiders as a peculiar genus is to be ascribed 
to O. F. Muztuer. Linnvus had not received these animals into his 
Systema nature; FABRIcIuSs in his Entomologia systematica, united the 
species then known to him with his genus Z’rombidium, and only after- 
wards, inhis 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&US, 
which is the typus of the genus Limnochares of LATREILLE, 
Limnochares LAtTR. Palps searcely longer than rostrum. Ros- 
trum conical, truncated; mandibles indistinct, with last joint subu- 
late. Ocelli four. Legs pilose, four posterior remote. 
37—* 
bo 
