MYRIAPODA. 483 



two pairs of legs, mostly terminated by a single hook, whether these segments may be undivideil 

 or separated into two semi-segments, each having a pair of these organs, and of which one 

 alone presents two spiracles.* 



The Myriapoda resemble, for the most part, small Serpents or Nereides, having the legs 

 closely placed together throughout the whole length of the body. The form of these organs 

 is also extended to the parts of the mouth. The mandibles are biarticulate, and immediately 

 succeeded by a piece in form of a lip, divided into four parts, with the divisions articulated, or 

 similar to small feet, and which, from its situation, corresponds with the tongue {languette) of 

 the Crustacea : then follow two pairs of small feet, of which the second pair is in the form of 

 large hooks in many, apjiearing to replace the four maxilla; of the latter animals, or rather the 

 two maxillae and lower lip of the Insects, being a kind of mouth-feet. The antennae, two in 

 number, are short, and rather thickened to the tip, or nearly filiform, /-jointed in some, much 

 more numerously jointed in others, and setaceous. The eyes are generally formed of an union 

 of minute ocelli; and if in some species they exhibit a facetted cornea, these facets are propor- 

 tionably larger, rounder, and more distinct than in the eyes of Insects. The spiracles are 

 often very small, and their number, in consequence of that of the segments, is often greater 

 than in the latter, where it never exceeds eighteen or twenty. The number of these segments 

 and that of the legs, increases with their age, a character which distinguishes the Myriapoda 

 from the Insects, the latter being always born with the number of segments which is proper 

 to them, and with all their true unguiculated feet developed at the same period, or at the time 

 of their quitting the pupa state. M. Savi, jun., Professor of Mineralogy at Pisa, has par- 

 ticularly studied the luli, and observed that they are destitute, on quitting the egg, of these 

 organs, so that these animals undergo a real metamorphosis. The situation of the sexual 

 organs, compared with the Crustacea and Arachnida, seems to point out the separation of the 

 thorax and abdomen. 



The Myriapoda live and grow longer than the other insects, and, according to M. Savi, at 

 least two years are required by some (luli), before the organs of generation appear. 



From these particulars we may conclude that these animals approach the Crustacea and 

 Arachnida, on one side, and the Insects on the other ; but, from the consideration of the 

 presence, form, and division of the tracheae, they belong to the latter class. 



[The relations of this tribe of animals are very ditRcult. Whilst Latreille and Kirby regard 

 them as entering the class of Insects, other authors have considered them as forming part 

 of the Arachnida; and M'Leay has separated them from both these classes, and formed 

 them into two orders, Chilopoda and Chilognatha, raising them, together with the two other 

 orders, Thysanura and Anoplura (or Parasita, Latr.), and certain annulated Vermes, into a 

 distinct class, to which he applied the name of Ametabola (changeless), which Leach had 

 proposed only for the spring-tailed insects and lice.] 



We divide them into two families, quite distinct, both in their organization and habits, and 

 formed by Linnaus into two generic groups. 



THE FIRST FAMILY OF THE MYRIAPODA,— 

 Chilognatha, Latr. (or the genus lulus of Linn.), — 

 Has the body generjilly crustaceous, and often cylindrical, the antennae rather thickened at the tips, or 

 nearly of equal thickness, and consisting of seven joints, two thick mandibles without palpi, very dis- 

 tinctly divided into two portions by a central articulation, with the teeth imbricated and planted in a 

 cavity at its upper extremity ; a kind of lip {lang%iette, or lower lip, composed, according to Savigny, 

 of the two pairs of maxillcE of the Crustacea) situated immediately beneath and covering them, being of 

 a crustaceous texture, flat, and divided at the outer surface, by longitudinal sections and notches, into 



'ely they are only to be considered as demise^^ments. Hcuce each 

 tnplete seijment has two pair of feet, one pair Iteing supernumerary, 

 eh segment in the other insects haWng only a pair of feel. 



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