98 ENTOMOLOGY. 



a group. They are preyed upon at different times of life by 

 different enemies. Worms, parasitic mites, and birds and 

 beasts constantly make war upon them, but these enemies 

 only confine their numbers within healthy limits; so that, 

 after all the inroads made upon them, there is still food 

 enough and room enough for each species to exist in its own 

 beetle-fashion in its own little beetle-world. 



The Coleoptera have been divided by LeConte into two 

 great groups or sub-orders, viz. : the Khynchophora or 

 weevils, in which the head is beaked and the palpi are 

 short and rigid, while the labrum is usually absent,* besides 

 other less apparent characters; and the genuine Coleoptera. 



The genuine Coleoptera, again, are divided by the number 

 of joints in their tarsi as follows: 



1. Hind tarsi with the same number of joints at least as 



the others (except in a few Clavicorns) . .ISOMERA. 



2. Front and middle tarsi 5-, hind tarsi 4-jointed. 



HETEROMERA. 



The Isomera are divided by LeConte and Horn into five 

 series, perhaps super-families: 



A. Fourth and fifth tarsal joints not connate: 



First three ventral segments connate: first divided by 

 the hind coxal cavities so that the sides are sepa- 

 rated from the very small medial part. ADEPHAGA. 

 First ventral segment visible for its entire breadth (ex- 

 cept in Khyssodida?) : 



Antennae clavate or capitate, very rarely serrate. 



CLAVICORNIA. 



Antennas serrate, very rarely clavate or capitate. 



SERRICORNIA. 



Antennae with a lamellate club, the opposing surfaces 

 with a very delicate sensitive structure ; legs fos- 

 sorial LAMELLICORNIA. 



B. Fourth and fifth tarsal joints anchylosed; the for- 



mer very small; antennas filiform, rarely serrate, or 

 feebly thickened externally PHYTOPHAGA. 



* In the Anthribidte and Rhinomaceridae the labrum is present 

 and the palpi are not rigid. 



