CHAPTER XIV. 



PHYLUM ARTHROPODA (continued}. 



Classes ONYCHOPHORA or PROTOTRACHEATA ; 

 MYRIOPODA ; and INSECTA. 



THESE three classes form a series of which winged insects 

 are the climax. The type Peripatus is archaic, and links 

 the series to the Annelids : the Myriopods lead on to the 

 primitive wingless insects. All breathe by tracheae tubes 

 which carry air to the organs of the body and all have 

 antennae ; hence they are often united under the title 

 Tracheata Antennata. 



First Class of Tracheata Antennata. ONYCHOPHORA or 



PROTOTRACHEATA. 



GENERAL CHARACTERS. 



The body is worm-like in form, soft skinned, and without 

 external segmentation. 



The appendages are a pair of prominent pre-oral antennce, 

 a pair of jaws in the mouth, a pair of slime-secreting oral 

 papillce, which development shows to be true appendages, 

 numerous pairs of short, imperfectly-jointed legs, each with 

 tivo claws, and a pair of anal papillce, which are rudi- 

 mentary appendages. The legs contain peculiar (crural] 

 glands. 



Respiration is effected by numerous unbranched trachea 

 with openings irregularly scattered. The heart is an elongated 

 dorsal vessel with valvular ostia. There is a series of 

 nephridia in the legs. The halves of the ventral nerve-cord 

 are widely separate. All are viviparous. 



