SOME WINGLESS INSECTS 



169 



of " rock- jumper " one of the bristle-tails (or Thysanura) some 

 species of which may be found in abundance along the sea-shore 

 just above high-water mark, and others among stones or vegeta- 

 tion in inland localities. The insect (Fig. 96) has the head 

 and body covered with beautiful scales which give it a dark 



FIG. 97. JAWS OF ROCK-JUMPER (Pctrobius brevistylis) . 



A, mandible (c, condyle ; a, apex; m, molar area), xis. 



B, terminal region of mandible (penultimate instar) ; the new 

 cuticle can be seen within, x 36. C, Hypopharynx (hy) 

 front aspect, with the left maxillula (Ml) slightly displaced 

 laterally, but retaining its membranous connexion with the 

 base of the hypopharynx (/, lacinia ; g, galea ; p, palp of 

 maxillula ; pe, peduncle of hypopharynx). D, Maxilla, hinder 

 aspect (c, cardo ; st, stipes ; /, lacinia ; g, galea ; p, palp). 

 X 18. E, Head of lacinia showing apex (a), " brush " (fr), and 



acute processes (c and d). F, Head of lacinia from a specimen 

 in the penultimate stage, showing apex (a), " brush " (6), and 

 acute processes (c and d) greatly worn, and new cuticle of 

 head formed within, x 60. After Carpenter, Irish Nat. 

 XXII. 



