152 



NATURAL HISTORY. 



Carboniferous period, have also furnished a peculiar species. A species referred to Geopkilus, and 

 therefore to the carnivorous order Chilopoda, occurs in the lithographic slates of Solenhofen. A few 

 Tertiary fossil species are known, and many occur enclosed in amber. 



DEVELOPMENT Of JULUS TERRESTRIS. (After Newport.) 



1, Embryo at rupture of egg ; 2, at end ot first day; 3. on third day : 4, on ninth day; 6, ncwly-lmiched Jiiluson seventeenth day; 6, on 

 nineteenth day; 7, on twentieth day; g, on twenty-sixth day. 



We divide the Myriopocla, including the abnormal type Peripatus, into four orders, as follows : 

 * Breathing Apertures regular Stigmata. 



1. CHILOPODA (Centipedes), with the antennae simple, the body depressed, the dor.-al and ventral 

 plates horny, united by a membrane ; the legs inserted in single pairs at the sides of the segments, 

 with the exception of the first two pairs, which are converted into mouth organs. 



2. CHILOGNATHA (Millepedes), with the antennae simple, the body usually convex, or even cylin- 

 drical, the dorsal plates bent round so as to meet the narrow ventral plates nearly in the middle line 

 of the body, each segment, after the fifth or sixth, with two pairs of legs. 



3. PAUROPODA, with branched antennae. 



t Breathing Apertures scattered. 



4. OXYCHOPHORA, worm-like, with a soft skin, simple antennae, and legs terminated by two 



claws. 



ORDER I CHILOPODA. 



The leading characteristic of the Myriopods of this order has been already indicated (p. 150). It 

 consists in the conversion of the first two pairs of legs into auxiliary organs of the mouth. In general 

 the dorsal part of the first two segments is reduced to a rudimentary condition, and their limbs are always 

 curiously modified. Behind the lower lip, of which the middle part is formed by the united halves of 

 the labium, while the lateral portions consist of the maxillae, the whole united into a single plate, the 

 limbs of the first body-segment make their appearance, the coxal portions being united in the middle 

 line so as to represent a sort of second labium, from which springs a pair of three-jointed organs like 

 palpi (the homologues of the first pair of legs). These parts are feebly developed, but the limbs of the 

 second segment attain a large size and a very remarkable structure. Their basal parts are expanded 

 into two broad, irregularly triangular plates, united in the middle, each of which bears a sickle-shaped 

 organ composed of four joints, representing the true limb. The basal joint of these hook-like parts is 

 of large size, and is followed by two broad but very short joints, and these again by a long, powerful, 



