a Family of Thysanura. 369 
tioned; and this I look upon as representing the cardo or hinge 
of the maxilla. The outer lobe (fig. 2 e) is membranaceous, and 
has near its anterior margin a small conical protuberance. 
There is a distinct palpiger (fig. 2 g) carrying a biarticulate 
palpus (fig. 2 f). The lingua (fig. 2 4) is in this genus propor- 
tionally very small, linguiform, and armed with short setz. The 
paraglosse (fig.2 77), on the contrary, are very large and bi- 
lobate. Of the muscles moving all these parts some are fixed 
to the inner surface of the skull, others to the oft-mentioned 
framework, which, in its turn, with all that is connected with 
it, can be pushed forward and drawn back by special sets of 
muscles, as shown in figure 2. 
The labium reminds one somewhat of the same organ in Ulo- 
nata, and consists of a deeply bifid plate covering the mouth 
from beneath. Its most striking feature is the existence of two 
large retractile warts, clear as water, which I suppose to corre- 
spond to the inflations discovered by Latreille on the labium of 
Machilis (Nouv. Ann. du Muséum, 1832,i. p. 171). But for this 
analogy, one might be tempted to look upon them as a kind of 
palparia which these blind animals might well need, but which 
are wanting in both pairs of palpi. I regret that my scanty 
material did not permit a proper examination of their histological 
structure. On each side of the fissure in the middle of the 
labium two component pieces (centres of chitinization) may be | 
distinguished, one behind the other, which perhaps correspond 
to the lobes observable on the third pair of appendages of the 
mouth in Ulonata. Further behind, a third pair of plates is 
observed, one on each side, which perhaps represent the stipites 
of the third pair of mouth-appendages ; and in an emargination 
on each of these plates, the short, conical, sparsely haired, and 
strongly chitinized palpus is inserted. 
There is no mentum. The hypostoma forms a rather large 
obversely cordate plate, placed near the posterior border of the 
underside of the head, between the inflected margins of the 
occiput. 
The antenne consist of many short joints furnished with 
verticillate setee; the individual joints are inversely conical or 
almost spindle-shaped, so that the general outline of the antenne 
becomes filiform or slightly moniliform. The last joint is 
smaller than the others and slightly conical. The antenne are 
placed on a protuberance which is separated from the skull by 
a fine suture, but does not constitute a basal joint, as it is im- 
moveable, the muscles of the antenne inserting themselves only 
on the base of the following moveable division. 
There is no vestige of eyes. | 
The skull is supported by a thin chitinous piece, which is 
Ann. & Mag. N. Hist. Ser.3. Vol. xx. 25 
