SCARABiEIDAE. 141 



the disk of the thorax is free from hair, and the antennae have 

 ten joints. 



Sub-Family III.— SCARAB^EIDAE PLEUROSTICTI. 



In this sub-family the abdominal spiracles are arranged ; the 

 second pair in the membrane connecting the dorsal and ventral 

 segments, the third on the outer limit of the membrane, and the 

 others in the dorsal portion of the ventral segments ; the last two 

 pairs diverge strongly, and are usually visible on the sides of the 

 abdomen, below the elytra, which do not cover the pygidium. 

 The clypeus is sometimes prolonged, but rarely concave, as in 

 most Melolonthidae, and in many the mandibles, though always 

 short, project beyond the clypeus. The mentum is sometimes 

 quadrate, sometimes pointed, with the ligula always corneous and 

 connate; antennas 9- or 10-jointed, with the club 3-jointed, rarely 

 elongated in the males; the epimera of the mesothorax reach the 

 coxae, and are variable in form; the tarsi are perfect, and the 

 onychium is distinct. 



Three tribes, separated by the following characters, exist; in 

 all of them the last spiracle is placed on the suture between the 

 fifth ventral segment and the propygidium, which are closely con- 

 nate, and is usually nearer the anterior than the posterior margin, 

 though in certain genera of the third tribe the reverse is the case. 



Claws of the tarsi unequal. Rutelini. 

 Claws of the tarsi equal ; 



Anterior coxa? transverse, not prominent. Dyxastini. 



Anterior coxa? conical, prominent. Cetoniini. 



Tribe I.- RUTELINI. 



These insects have entirely the form of certain Melolonthida?, 

 and are only distinguished from them by the position of the spir- 

 acles, and the unequal size of the tarsal claws, which are chelate. 

 In our genera the tarsi are short, with the joints cylindrical and 

 closely connected ; the epimera of the mesothorax have in some 

 genera a tendency to ascend between the thorax and elytra, as in 

 Cetonia; the side pieces of the metathorax are narrow, with the 

 epimera visible. The species live on leaves of trees; some ore 

 ornamented with metallic colors, and one of them, Plusiolis glo- 



