256 COLEOPTEKA OF NORTH AMERICA. 



Sub-Family III._SCARAByEIDAE PLEUROSTICTI. 



Ill 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 

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

 ]tairs diverge strongly, and are usually visible on the sides of the 

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

 'I'he clypeus is sometimes prolonged, but rarely concave, as in 

 most Melolouthinse, and in many the mandibles, though always 

 fehort, project beyond the clypeus. The mentum is sometimes 

 quadrate, sometimes pointed, with the ligula always corneous and 

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

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

 co.xic, and are variable in form ; the tarsi are perfect, and the 

 onychium is distinct. 



Three tribes, sc|)arated by the following characters, e.xist ; in 

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

 lifth 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. 



("laws of the tarsi inu>qiial. Rttelini. 

 (Uaws of the tarsi equal ; 



Anterior coxa; transverse, not prominent. Dynastini. 



Anterior coxse conical, prominent. Cetonmni. 



Tribe I.— RI:TELI\I. 



These insects have entirely the form of certain Mololonthinje, 

 and are oidy distinguished from them by the position of the spira- 

 cles, and the unequal size of the tarsal claws. In onr genera the 

 tarsi are short, with the joints cylindrical and closely connected: 

 the epimera of the mesothora.\ have in some genera a tendency 

 to ascend between tht^ 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 are ornamented with 

 metallic colors, and one of them. Plusioli's gloriosa. from the 

 copper-mines of the Gila, of a pale green color, with the margins 

 of all the parts of the body and broad stripes on the elytra of a 

 j)ure polished gold color, is the most beautiful Coleopterous insect 

 known to us. 



