OF WASHINGTON. 217 
its limbs, thoroughly mouthing first one tibia and tarsus and then another, 
then stretching out one front leg over an antenna and drawing it between 
its maxillae, gradually passing it forward to the tip. 
For such cleansing work the mouth-parts are well adapted. The tip of 
the labium is slightly bristly and is furnished with a groove, into which the 
antenna fits in passing through. The labium is prehensile and fills the 
part of a lip better than any more solidly chitinous labhrm would. It plavs 
freely on its clypeal hinge and bends readily on itself, being capable of 
partly rolling, in fact. The mandibles proper, which are very large and 
strong, perform no part in this process. The maxillae are the important 
agents, and the base of their inner lobe the lacinia is fitted with a broad 
cushion, thickly studded with bristles, well fitted to remove all dust par- 
ticles from the limb passing between them. The lacinia presents one or 
two very interesting points. It is strong and mandible-like and furnished 
with a strong, acute, sickle-shaped tooth at tip. At the base of this tooth 
is a most peculiarly shaped digitus, differing widely from the correspond- 
ing organ in any Coleopterous insect and from any Orthopterous insect, 
the mouth-parts of which I have seen figured, and even from the corre- 
sponding part in Blatta oriental's, as figured by Messrs. Miall and Denny 
in their work upon this species. It is straight, bent at tip, and furnished 
on the inner edge near its tip with three equidistant comb-like teeth. The 
galea is narrow at base, but towards tip broadens and rolls laterally on 
itself, making an almost perfect hood, which surrounds the tip of the 
lacinia when not in use. It shows plainly the propriety of its' name. The 
tips of the fiaraglossce are also cushion-like and furnished with an abun- 
dance of soft bristles, and, undoubtedly the antenna, in being drawn 
through the mouth, held in place 1 by the hooked tips of the lacinice, is 
brushed below by \.\\t paraglossce as well as by the labium, and on the 
sides by the cushioned bases of the lacinice. 
The labium as a. whole is very highly developed, greatly more so than 
in Hymenoptera, Coleoptera, and other mandibulate insects, including 
such Orthoptera as have been figured. As pointed out by Comstock, who 
seems to have studied only this one organ in the cockroach mouth and who 
does not mention the maxillar peculiarities just mentioned, it is bifid quite 
to the mentum.; but, as I have observed by the dissection of an individual 
just killed and not stiff, although the suture through the hard chitine ex- 
tends to the ligulo-mental suture the two halves of the ligula cannot be 
separated except at tip, for a short distance only below the paraglossse, a 
strong hypodermal membrane holding them firmly together. The para- 
glossce are very large, articulating with the two halves of the ligula with 
considerable play and fitting closely together at their inner borders when 
at rest. They are stout, broadly oval (seen from below) , and furnished with 
many soft bristles. Each bears, moreover, at its inner tip a little articu- 
lated bristled knob, which has received no name. At the inner tip of each 
half of the ligula, mesiad of the paraglossse, is another unnamed sclerite, 
triangular in shape and also bristly. The homology between this bifid 
