148 Prof. J. Wood-Mason's Murphological Notes 



rudiment, which, however, persists throughout life ; find 

 in the still higher cockroach even this is absent in adult 

 life, being only seen as a transient condition in the embryo. 



Fis. 1. 



Fig. 1. 3Jac7iilis {Petrohius) onaritima. Mnndibles, viewed from above ; 

 a, exopodite, h, endopodite, 1, 2-|- 3, 4, the three joints, x, median 

 chitinous plate to which the great flexor muscles are attached. 



2§. The mandibles (fig. 1) oi Machilis have been figured 

 in outline, and briefly described by Sir John Lubbock, but 

 both he and all other writers have apparently overlooked 



