a Family 0/ Thysanura. 365 



side by side, being far more closely related to one another than 

 either of them is to LepismBe. 



Campodeae. 



Pedes cursorii, tarsis distinctis, elongatis, biungulatis. 

 Corpus elongatum, abdomine distincte decemarticulato. 

 Spiracula perspicua, saltern terna. 



Abdominis laminae ventrales septem priores appendiculatse. 

 Cerci duo, e segmeuto decimo, ultimo, ori^ntes. 

 Antennae setacese vel filiformes. 



This family comprises as yet only two genera {Campodea, 

 Westw., and Japijx, Halid.), and therefore coincides with Japy- 

 gidse, 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 Podurse, is therefore superfluous. 

 The tarsus consists only of one joint, but is otherwise well 

 developed and of considerable length ; whilst the Podurse are 

 without a distinct foot. In point of fact, I am most inclined to 

 regard the part which carries the claw in Podurse 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 Campodese always have two true 

 claws. Many Podurse are certainly described as having 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 difl*erence has been 

 pointed out by Professor Schiodte in his paper " De Metamor- 

 phosi Eleutheratorum Observationes"(Naturhistorisk Tidsskrift, 

 ser. 3. vol. i. pp. 207, 209; iii. pp. 150, 153, 194), between the 

 larvse 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 prsetergum, posttergum, prse- 

 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 



