LYSIANASSA COSTJl. 75 



appendage of only two. The inferior antennae do not 

 reach beyond the extremity of the superior ; they are 

 much more slender, and have a considerable portion of 

 the peduncle covered by the lateral walls of the head. 

 The epistoma considerably projects, and is formed into 

 a wedge-like process, rounded and projecting above, 

 receding towards the inferior margin, where it corre- 

 sponds with the lower extremity orcutting margin of the 

 mandibles. 



The mandibles, d, are long and narrow, narrower 

 a little towards the cutting margins than at the base, 

 which articulates with the head ; the molar tubercle is 

 long, narrow, and slightly curved : the incisive margin 

 is smooth, a form which, as far as we are aware, is 

 peculiar to this subfamily, and suggests the idea of 

 its being adapted for cutting vegetable substances ; the 

 blade is hollow, or cup-shaped, being separated from the 

 remainder of the mandible by a sudden constriction or 

 neck ; the anterior margin, where it is increased in 

 width, is produced into a small tubercle ; the man- 

 dibular appendage is three-jointed, which is a very 

 common form in the Order. The pair of foot-jaws, 

 gy have the fifth joint very long, being much longer 

 than the sixth. The third and fourth joints are pro- 

 duced into large squamiform plates, which nearly reach 

 to the extremity of the fifth joint ; the inner margin 

 of the squamous plate of the fourth joint is slightly 

 scalloped, and furnished with rudimentary spinules 

 which respectively correspond with the scollops at the 

 margin of the plate. These spinules, although of a 

 very obsolete character, appear to differ very consi- 

 derably in different species ; and we think that they 

 may be found of very considerable service in detecting 

 the relative value of species, where it may be desirable 



