250 COLEOPTEUA OF NORTH AMERICA. 



B. Pleurostict Melolontiiin^. 



The mandibles and labriim 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- 

 deiined 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. Tibi?e with one spur, which is sometimes obsolete ; tarsi without ony- 



cliium, front and middle ones with two chelate, unequal claws, 

 except in one species, where the middle tarsi have but one claw ; 

 hind tarsi with a single claw ; last spiracle placed on the suture 

 lietween the fifth ventral and propygidium, which are connate ; 

 ventral segments connate; side pieces of metathorax broad. 



I. IIOPLIINI. 

 Middle coxffi contiguous. 1. Hoplumi. 



B. Middle and hind tibise with two spurs ; tarsi with distinct bisetose 



onychium and equal claws ; 



a. Last sj^iracle in the fifth ventral, which is not connate with tlie 



propygidium ; side pieces of metatliorax narrow ; ventral seg- 

 ments six, free ; anterior coxse conical, prominent. 



II. SERICINI. 



Labrum separate ; claws chelate. 2. Dicheloxycuini. 



Labrum connate ; claws not chelate. 3. Sericiki. 



b. Last sj)iracle placed on 'the suture between the fifth ventral and 



the propygidium, which are closely connate. 



III. MELOLONTHINI. 

 Anterior coxse prominent, conical ; 



Ventral segments six, not connate; 



Hind legs slender. 4. Macropactylini. 



Hind legs thick. 5. Seeicoidini. 



Ventral segments five, subconnate. 6. Diplotaxini. 



Anterior coxse transverse, not prominent ; ventral segments six ; 



Ventral segments connate. 7. Melolonthini. 



Ventral segments not connate. 8. Macrophyllinj. 



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

 iini)crfectly developed. 



