840 THE AMERICAN NATURALIST. [Vor. XXXIV. 
the front of the head, close above the first pair of limbs 
(chelicerae) ; it consists of two flat, lancet-shaped bodies, which 
by a common basal part are attached to the head, against which 
they are pressed. The second couple forms two blades, which 
are placed close up to the sides of the head above the coxa of 
the second pair of limbs, and which, though deviating some- 
what in shape, in quality very much resemble the first couple 
of blades; they turn, at least when in repose, horizontally 
forward and outward. As they are articulated to the head, it 
is not unlikely that they can move. Morphologically they are 
hairs." Hansen and Sórensen do not pretend to have demon- 
strated the sensory function of these structures. 
The Danish investigators have also given an accurate account 
of the mouth of Koenenia.! «It is simpler than in any other 
arachnid, nay, than in almost all other Condylopods, no limbs at 
all participating in its forming, and we are of opinion that in. 
this respect the mouth of Kcenenia, simple and plain as it 
is, presents great interest. It has the shape of a downward 
sloping protruding knot, and its opening consists of a relatively 
large split extending not quite up to the base of the mouth 
eminence. Seen from below, 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 fore- 
most or uppermost of these flaps no doubt constitutes the 
organ which in other Arachnida one of us (William Sóren- 
sen) 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, epis- 
toma, camerostoma) . . . We entertain some doubts as to 
how the lower or hindermost flap is to be understood from a 
morphological point of view. So for the present we will call it 
hypostoma, 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 
on the labrum. The labrum, as well as the hypostoma, 1$ 
1 Loc. cit., pp. 226, 227. 
