HIGH SCHOOIi ZOOLOGY. 211 



in the Insecta, into thorax and abdomen. There are no wings, 

 and the niaxillse may only be present in one pair. Most of the 

 Myriapods fall into two orders, tlie Chilopoda and Chilognatha, 

 the former including carnivorous forms (Centipedes, Fig. 145), 

 _ the latter, forms which live in decaying vege- 

 table material (Millipedes and galleyworms). 

 The parts of the mouth are adapted to their 

 labits, for in the Chilopoda the first pair of legs 

 end in powerful claws perforated by the duct 

 of a poison-gland, and are turned forwards to 

 supplement the three paii's of jaws. In the 

 Chilognatha, on the other hand, there is only 

 one pair of maxillee below the mandibles, and 

 they are united to form a labium. The two 

 Fig. 145.-Scutigera. groups further difier in that the Centipedes 

 have only one pair of legs to each segment, the Millipedes two i 

 and that, while the Centipedes resemble the insects in the 

 position of the opening of the oviduct, this is near the head in 

 the Millij^tedes. It will be apparent from what follows that 

 these are much more important structural peculiarities than we 

 find separating the orders of Insecta from each other. 



Certain tropical worm-like forms {Perlpatus) which have the habits of 

 Millipedes, but whose segments bear unjointed appendages terminating 

 in hooks, are of interest as being intermediate between the Vermes and 

 the lower Arthropoda. A separate class (Protracheata) has been formed 

 for their reception. 



29. Returning to the locust audits allies, which are described 

 as the Orthoptera proper {0. geuuina), we must now proceed 

 toward thfe higher orders of insects, glancing, in the first place, 

 at cex-tain forms associated by naturalists with the Orthoptera, 

 on account of the structure of the mouth-parts and the absence 

 of a metamorphosis, but differing from them in that both pairs 

 of wings are alike. The wings resemble those of the nerve- 



