134 COLEOPTERA OF NORTH AMERICA. 



Anterior coxae large, prominent, conical ; mandibles and labrum 

 beneath the reflexed cljpeus ; antennas 9-jointed, short ; club small, 

 3-jointed; abdomen very small, with the ventral sutures entirely 

 effaced, last segment free, conical ; pygidiurn slightly prominent ; 

 elytra rounded at tip ; epimera of mesothorax small, extending to 

 the coxa?; side pieces of metathorax narrow, epimera covered; 

 legs stout, posterior thighs large ; tibiae thick, conical ; tarsi very 

 long ; claws diverging, slender, with a small bisetose onychium ; 

 anterior tibiae without spurs, posterior tibiae with two spurs. 



Clypeus concave, rounded ; mentum linear ; claws simple. Lasiopus. 



Clypeus flattened, parallel, incised each side, and marked with a transverse 

 suture ; mentum trapezoidal ; claws divided. Oncerus. 



Lasiopus is found in Texas, Oncerus in California, each repre- 

 sented by one species. They are the smallest Melolonthida? 

 known to me, and live on flowers ; the upper surface is glabrous, 

 but the legs are fringed with long hairs. Oncerus resembles in 

 form the European Cbasmatopterus, but the clypeus is double 

 as in Diphucrania. Lasiopus exactly resembles in appearance 

 Aclopus Er., which, however, has the labrum and mandibles 

 porrected as in the preceding tribe. 



b. Pleurostict Melolonthidae. 



The mandibles and labrum are placed under the clypeus in all 

 of our genera, although prominent in some foreign genera ; the 

 posterior pair of spiracles varies in position ; in some groups it 

 is external to the suture between the propygidium and the fifth 

 ventral segment, in others it is placed directly on the suture, 

 which in Diplotaxes is almost obliterated. Although the sub- 

 tribes appear to be quite natural groups, and of equal value, it 

 is difficult, on account of the absence of many typical forms from 

 our fauna, to combine them in such manner as to form well- 

 defined tribes, such as are seen in the previous sub-family ; there 

 would appear, however, to be three indicated, which, with their 

 sub-tribes, may be thus tabulated, all represented in our fauna 

 having normally developed oral organs.* 



A. Tibiae with one spur, which is sometimes obsolete ; tarsi without ony- 

 chium ; claws chelate, unequal ; last spiracle placed on the suture 



* In the foreign tribe Pachypodini the oral organs are very feebly and 

 imperfectly developed. 



