HANSEN AND SÖRENSEN: THE ORDER PALPIGRADI. 227 
this split is slightly crescent-shaped and curves towards the front. 
It is bordered by two flaps which along its margins are furnished 
with a rather strongly chitinized »list» or frame, which seems to 
become somewhat weaker towards the corners of the mouth. The 
foremost or uppermost of these flaps no doubt constitutes the 
organ which in other Arachnıda one of us (WILLIAM SÖRENSEN) 
calls the labrum (or, when divided into two parts, the clypeus 
and the labrum), but which otherwise (according to the different 
authors) goes by rather varying names (rostrum, epistoma, ca- 
merostoma). As its shape is shown with sufficient distinctness 
in figg. 7 and 8, we will content ourselves with saying that the 
somewhat more vaulted part of its lower side is closely covered 
with extremely short setæ, most of which turn straight backward. 
From the inside of its frame proceed five very powerful and 
comparatively long setz, pointing inward into the mouth. — We 
entertain some doubts as to how the lower or hindmost flap is 
to be understood from a morphological point of view. So for 
the present we will call it yfostoma, as we consider this name 
morphologically tolerably indifferent. It is furnished outwardly 
with very tiny backward turning hairs placed somewhat less close 
together than those of the labrum. 
The labrum, as well as the hypostoma, is movable, so as 
to allow the mouth to open and to close. The muscles, which 
by the by we have not examined more closely, are very strong. 
The Limbs, as already stated by Grassi, show a very 
simple structure, being, with the exception of the first pair, very 
uniform in shape. The first pair (figg. 9 and 10) correspond 
entirely with the type appearing in Opzlzones. In its minuter 
details of form, however, it does not remind us of any genus 
of Opzliones known to us. The very powerful first joint is 
slightly compressed at its base towards its exterior side so as to 
make this compressed part extend somewhat downward beside 
the mouth (figg. 2 and 3). We emphasize this fact because we 
do not know any other animal among the higher Arachnida in 
which this pair, of limbs is not placed gwzfe in front of the mouth. 
The basal joint is furnished with a number of hairs, the longest 
of which, being placed on its sub-proximal part, are monolate 
5 
