CHAPTEE XVIII 



TRACHEATA 



Class II. MYRIAPODA 



Myriapoda -f '^^ilopo'l* — IMhobms, Scolopendra, Scutigera. 



\ Diplopoda (Chilognatha) — lulus, Polyxemus, Fauropus. 



Chaeacteeistics. — Tracheate Arthrojpoda with a distinct head 



and a number of similar somites; no distinction of thorax 



and abdomen. A pair of antennae, mandibles, and maxillae, 



and numerous six- or seven-jointed clawed legs present. 



Of all the Tracheata, with the exception of Feripafus, the 



Myriapoda exhibit least signs of specialisation in their external 



structure. The segments posterior to the head, which in the 



Geophilidae may amount to some hundreds, are all very 



similar, and they are not externally grouped together into any 



regions such as thorax or abdomen. 



The Myriapoda are divided into two orders : (i.) the Chilo- 

 poda and (ii.) the Diplopoda or the Chilognatha. 



Order 1. CHILOPODA. 



Chaeacteeistics. — Myriapoda with dorso-ventrally compressed 



body. Antennae long, with many segments. The second pair 



of pastoral limbs form the poison dates. One sternum and 



one pair of legs to each segment. Genital orifice posterior. 



Stigmata lateral, tracheae branching and anastomosing. 



Zithobius forfcatus is the commonest English centipede ; it 



is found all over Europe, in the summer living under stones, 



leaves, etc., and in the winter hidipg itself in the earth. It is 



about one to one and a half inch long, and of a chestnut- 



