CHAPTER XIV. 



PERIPATUS, MYRIOPODS, AND INSECTS. 



Arthropoda. Sub-division Tracheata Antennata. 



Classes Prototracheata. — Peripatus. Myriopoda. — Centipedes 

 and Millipedes. Insecta. — Insects. 



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 the title Tracheata Antennata. 



First Class of Tracheata Antennata. — 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 antenna, 

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

 papilla, which development shows to be true appendages, 

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

 two claws, and a pair of anal papilla, which are rudi- 

 mentary appendages. The legs contain peculiar (crural) 

 glands. 



Respiration is effected by numerous trachea with openings 

 somewhat scattered on the surface of the body. The heart is 

 simply an elongated dorsal vessel with valvular openings. 

 There is a series of excretory tubes or nephridia. The halves 

 of the ventral nerve-cord are widely separate. 



