ARACHNOIDEA. 581 
Atax F apr. (in part), Ducks (and Arrenurus ejusd.), Palps 
subulate, with last joint faleate, or unguiculate. Ocelli two, lateral, 
distant. Body in the males of some species narrowed posteriorly 
and produced into an appendage truncated or cylindrical (Arrenurus 
DuGEs). 
Add sub-genera: Nesea, Piona, Hygrobates’, Hydrochoreutes, 
Atractides, Acercus, Marica Kocu. 
Comp. UVebersicht des Arachnidensystems, 111tes Heft, erst Abtheil. 1842, 
and P. T. Van BrenepDEN Recherches sur l Atax ypsilophora, Hydrachna 
concharum. Mém. del’ Acad. royale de Belgique, Tom. XXIv. 
Family VIII. Sdellea. Rostrum subulate, separated from 
body by stricture, often large, resembling a head. Body oblong, 
mostly parted by a transverse groove or stricture between the 
second and third pairs of feet. Palps inserted at the base of ros- 
trum, lateral, divaricate, large. Mandibles terminated by an in- 
curved claw or two small fingers. Ocelli mostly distinct, four. 
Feet cursorial, attenuated towards the apex, terminated by two 
small claws. 
Bdella Larr., Scirus Herm. Palps filiform, geniculate or in- 
curved. Feet subequal. 
Bdella Ducks, Kocu, Ammonia Kocu, Scirus Ducks, Kocu, 
Eupalus Kocu. 
Comp. Uebersicht des Arachnidensystems, l1tes Heft, 3, pp. 73—80.—Sp. 
Bdella vulgaris Latr., HERMANN Mém. Aptér. Pl. 3, fig. 9, Koon, HERRICH- 
Sco#FFrer D. Ins. Heft 167, tab. 8. 
Cheyletus Latr. Palps thick, incurved, filiform. Feet slender, 
anterior longer. Ocelli none or indistinct. 
See figures in Kocu, Herricu-Scu#rrer, Heft. 167, Tab. 20, 
21, 22. 
Family IX. Trombidina. Palps chelate, with last two joints 
opposite, the external (penultimate) representing an incurved 
claw. eet terminated by two small claws, cursorial. 
Trombidium Fasr. (exclusive of some species). Two mandi- 
bles horny, unguiculate, included in labium. Body suboval or 
1 Tn the neighbourhood of Hydrobates Kocu probably Pontarachna PHILIPPI ought 
to be placed, if it is to be considered a distinct genus; a very small Hydrachna observed 
in the bay of Naples. Annals of nat. History, vi. 1841, pp. g8—rI00. 
