185 
not know any statement that the animals stridulate, 
I still look upon it as unquestionable that we here 
have a stridulating apparatus, built, indeed, very 
differently from those which, as far as I know, are 
found in /nsecta, Aranece, Spherotherium and Deca- 
poda; because in Solpuga we find 2 similarly 
rifled planes rubbing against each other, a structure 
occurring nowhere else. [ may still add that the naked 
plane is slightly arched. 
A similar development of the stridulating apparatus 
is found in the other species of the genus Solpuga 
known to me. In Galeodes (G. orientalis Stol., G. 
araneoides Pall., G. græcus C. Koch, G. scalarıs C. 
Koch) it is considerably slighter with shorter keels, 
occupying but about the half of the anterior margin of 
the naked plane; in Datames (geniculatus? C. Koch) 
and in a species of the genus Zombis almost as in 
Galeodes. In Rhax annulata? (unfortunately the 
only species of the genus known to me) the interior 
side of the mandibles is much flatter than in the former 
genera, and the naked plane comparatively shorter with 
uniformly and strongly curved anterior margin, the c. 
10 keels are all rather short, but vigorous, the middle 
ones the longest. In Cleobis Cubæ Luc. (the sole 
species of Cleobis known to me) the apparatus attains 
a very high development (Tab. II, fig. 9). The naked 
area is almost as long as it is high, the furrowed 
portion occupies but little more than the upper half, 
but in contrast to the former genera more 
than 2/3 of its length, owing to the uncommon 
length of the c. 9 keels. Furthermore the naked area 
is uncommonly arched thuswise that the top one but 
three keel becomes the most prominent at the same 
time as it is the longest and thickest; henceforth the 
keels decrease sligthly in length downwards. In a very 
