24 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 33- The hy- 

 popharynx (h) 

 and maxillulse (m) 

 of Scolopendrella 

 (After Hansen). 



3 2 , mx) resemble in a striking degree the maxillae of insects, consisting 

 of a long stipes, (5), which bears a minute palpus, (p), and an outer 

 and inner lobe ; the second maxilla or labium (Fig. 

 32, /) also resembles the corresponding part of the 

 more generalized insects, being composed of a pair 

 of united gnathites. 



The legs of the first pair are reduced in size and 

 in the number of their segments. The other legs 

 consist each of five segments; the last segment 

 bears a pair of claws. Excepting the first two 

 pairs of legs, each leg bears on its proximal seg- 

 ment a slender cylindrical process, the parapddium (Fig. 34, p). 

 These parapodia appear to correspond with the styli of the 

 Thysanura. 



At the caudal end of the body there is a pair of 

 appendages, which are believed to be homologous 

 with the cerci of insects (Fig. 35, c). 



A striking peculiarity of the symphylids is that 

 they possess only a single pair of tracheal tubes, 

 which open by a pair of spiracles, situated in the 

 head beneath the insertion of the antennas. 

 The members of this class are of small size, the 

 larger ones measuring about one-fourth inch in 

 length . They live in earth under stones and decay- 

 ing wood, and in other damp situations. Imma- 

 ture individuals possess fewer body-segments 

 and legs than do adults. 



Less than thirty species have been described; 

 but doubtless many more remain to be discovered. 

 The known species are classed in two genera : 

 Scolopendrella and Scutigerella. In the former the 

 posterior angles of the terga are produced and 

 angular ; while in the latter they are rounded. 



A monograph of the Symphyla has been published by Hansen ('03). 



Fig. 34. A leg of 

 Scolopendrella; 

 p, parapodium. 



Fig- 35- The caudal 

 end of the body of 

 Scolopendrella; I, 

 leg; c, cercus (After 

 Latzel). 



CLASS MYRIENTOMATA 



The Myrientomatids 



The members of this class are small arthropods in which the body is 

 elongate, as in the Thysanura, fusiform, pointed behind, and depressed; 

 it may be greatly extended and retracted. The antenna and cerci are 



