ARACHNIDA — ACARl. 
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species, one from Portugal, the rest from Central America (to the latter, 
several species, figured in Guer. Mag. d. Zool., are to be added). 
OPILIONES. 
Gervais (Mag. d. Zool. 1842, Arachn. pi. 2-5) has described and figured 
two new species : Gonyleptes planiceps, Guer., from the Straits of Ma- 
gellan, and Stygmis injiatus, Guer., from Cayenne ; and characterized a 
new genus Phalanyodes, which is nearly identical with Pachylus, Koch ; 
defining also the species Ph. anacosmetus, perhaps from New Holland — 
it is probably the same as P. granulatus, Roll., from Chili. There is 
also a species of Cosmetidce added, under the name of Cosmetus fiavi- 
cinctus. It is not a true Cosmetus, as it has double protuberances on 
the hinder part of its back ; but whether it be a Flirtea, or one of Koch’s 
allied genera, is not certain, as the number of the tarsal joints is not 
noticed. It is found at Bogota, and is distinguished from the other Cos- 
metidoe by the rough spinous hind legs. 
AC AHI. 
Our acquaintance with this order has been essentially increased by 
Koch’s “ Ubersicht des Arachnidensystems, 3 Hft. 1 und 2 Abtheil.” 
These two numbers extend to Hydraclinidce and Trombididce. 
The first division of the mites is formed of the Water-acari, with 
swimming feet, in two families : River-acari, Hygrohatides, and Pond- 
acari, Hydrachnides, the former having two, the latter four eyes. The 
Hygrohatides consist of the genera Atax, Dug. ; Nescea, K. ; Piona, K., 
Hygrohates, Hydrochoreutes, K. (including the genus Spio ) ; Arrhen- 
urus, Dug. ; Atractides, Acercus (formerly Tiphys, K.) ; Diplodontus, 
Dug. ; Marica, K. The Hydrachnides consist of Limnesia, K. ; Hy~ 
drachna, Miill. ; Hydryphantes, K. ; Hydrodoma, K. ; Eulais, Latr. 
As a second division, the author correctly separates the Marsh-acari, 
which, although living in the water, or at least in moist places, have no 
swimming feet, and therefore have not the power of swimming. These 
Acari have a long thick proboscis, narrowed by steps [stufenweise abge- 
setzten], seven-jointed legs, of which the two anterior pairs are separated 
from the two posterior pairs by a wide space. To this group belong the 
genera Limnochares, Latr., Thyas, K., both living in water, and creep- 
ing awkwardly under it; Smaris, Latr., and Alycus, K., both living on 
moist ground or under wet moss. 
The Land-acari form the third division (as the author has afterwards 
corrected it ; for, by mistake in the text, Marsh-acari is printed), having 
seven-jointed legs, without moveable bristles on them, and a little hook 
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