24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8o 



and a fourth (q), apparently forming the dorsal part of the coxa 

 (Cx), he calls the " coxopleure." When compared with Eoscntomon 

 (fig. 8), it appears more likely that the plate over the coxa in Lithobius 

 should be the trochantin, of which the more ventral sclerite (/>) may 



Fig. 9. — Coxa and pleurites of one segment of a centipede, Lithobius forficatus. 

 (Verhoeff, 1903.) 



Cx, coxa; 0. eupleural sclerite (anopleure of Verhoeff) ; p, precoxal sclerite: 

 q, coxal sclerite (coxopleure of Verhoeff) ; Tn, trochantin (katopleure of 

 Verhoeff). 



be a part, though the latter might correspond with the precoxal sclerite 

 (/) in Eoscntomon. In Lithobius sp? (fig. 32 B) there is only one 

 plate dorsal to the coxa. Though the Chilopoda and the Protura cannot 

 be regarded as related except indirectly through some remote common 



Fig. 10. — Lateral view of mesothorax of Japygidae. 



A, J a pyx sp., pleural region occupied by trochantin (Ttt) curving over base 

 of coxa (Cx), and by two lateral extensions (/, in) from apotomal folds (i, k) 

 of sternum. (Spiracles not seen in this species.) 



B, Heterojapy.v sp. (large species from Australia), showing spiracles. Sp.y. 

 prothoracic spiracle ; Sp-i, mesuthoracic spiracle ; a metathoracic spiracle in 

 corresponding position ; Sp, first metathoracic spiracle, at upper end of pleural 

 apotomal folds. Other lettering as on figure 6. 



ancestor, yet it does not appear impossible that their pleural sclerites 

 may have been derived from the same basic structure. 



In the Japygidcc, the pleural structure api>ears, at first sight, to 

 have little in common with that of the Protura. In some forms 

 (fig. TO B) there is a tergopleural fold in the me.sothorax and meta- 



