a Family of Thysanura. 365 
side by side, being far more closely related to one another than 
either of them is to Lepisme. 
Campodez. 
Pedes cursorii, tarsis distinctis, elongatis, biungulatis. 
Corpus elongatum, abdomine distincte decemarticulato. 
Spiracula perspicua, saltem terna. 
Abdominis laminz ventrales septem priores appendiculate. 
Cerci duo, e segmento decimo, ultimo, orientes. 
Antenne setacee vel filiformes. 
This family comprises as yet only two genera (Campodea, 
Westw., and Japyx, Halid.), and therefore coincides with Japy- 
gid, Hal.; but I prefer to name it as I have done in obedience 
to the old rule that a family name is always to be derived from 
the oldest established genus in the family. 
The legs are upon the whole well developed, and allow of 
rapid movement ; a special apparatus for this purpose, such as 
the springing-apparatus of most Podure, is therefore superfluous. 
The tarsus consists only of one joint, but is otherwise well 
developed and of considerable length; whilst the Podure are 
without a distinct foot. In point of fact, I am most inclined to 
regard the part which carries the claw in Podure simply as 
an empodium, which sometimes may be almost evanescent, at 
other times sufficiently distinct, with or without an onychium, 
but with only one claw, whilst Campodez always have two true 
claws. Many Podure are certainly described as haying two 
claws; but the supposed second claw is merely a claw-formed 
onychium, as may be seen from its place of insertion on the 
empodium, and its position relatively to the only real claw. It 
will be remembered that an analogous difference has been 
pointed out by Professor Schiddte in his paper “ De Metamor- 
phosi Eleutheratorum Observationes” (Naturhistorisk Tidsskrift, 
ser. 3. vol. i. pp. 207, 209; ui. pp. 150, 158, 194), between the 
larve of Carabi, Dytisci, and Gyrini on one side, and those of 
all other families of Eleutherata on the other side. 
The body is upon the whole rather flat and elongated; the 
several rings are distinctly separated, particularly those of the 
thorax, in each of which separate pretergum, posttergum, pre- 
sternum and poststernum, are often observable, besides the ordi- 
nary dorsal and ventral shields. The spiracles are easily dis- 
tinguished, and at least three in number on each side—namely, 
one for each of the thoracic rings. This latter peculiarity is 
unique among insects ; for in other cases where three pairs are 
to be seen on the thorax, the hindermost pair belongs really to 
the segmentum mediale or to the metathorax and segmentum 
