6o ARTHROPODS 



E. Metasternum with an antecoxal piece, separated by a 

 well-marked suture reaching from one side to the other, 

 and extending in a triangular process between the hind 

 coxae. 



F. Antennae eleven-jointed; hind coxae mobile, and of 

 the usual form; habits terrestrial. 

 G. Antennae inserted on the front above the base .of 



the mandibles Cicindelidae. 



GG. Antennae arising at the side of the head between 

 the base of the mandibles and the eyes. .. .Carabidae. 

 EE. Metasternum either with a very short antecoxal piece, 

 which is separated by an indistinct suture, and which is 

 not prolonged posteriorly between the coxae, or without 

 an antecoxal piece. 

 F. Metasternum with a very short antecoxal piece. 



Amphizoidae. 

 FF. Metasternum without an antecoxal piece. 

 G. Legs fitted for swimming. 



H. With only two eyes.' Dytiscidae. 



HH. With four eyes, two above and two below. 



Gyrinidae. 



GG. Legs fitted for walking Rhyssodidae. 



DD.. Ventral part of the first segment of the abdomen visible 

 for its entire breadth. 

 E. Antennae with a lamellate club. 



F. Plates composing club of antennae not capable of 



close apposition, and usually not flattened. . .LMcani'dae. 



FF. Plates composing club of antennae capable of close 



apposition, and flattened Scarahaeidae. 



EE. Antennae either clubbed or not, but when clubbed 

 not lamellate. 



F. Elytra short, leaving the greater part of the abdo- 

 men exposed ; the suture between the elytra when closed 

 straight; wings present, and when not in use folded 

 beneath the short elytra ; the dorsal part of the ab- 

 dominal segments entirely horny. 



