122 COLEOPTERA OF NORTH AMERICA. 



longed internally, forming a club of lamellae, which may be 

 brought close together; first joint always elongated, second 

 thicker than the following. 



Prothorax with the side pieces not separate; anterior coxal 

 cavities transverse, very large, closed behind. 



Mesosternum short, frequently very narrow; side pieces 

 attaining the coxae, except in Trogini. 



Metasternum large; side pieces variable in form. 



Abdomen with six, rarely five, ventral segments. 



Legs fossorial; anterior coxae large, transverse, sometimes 

 subcorneal and prominent, sometimes not prominent ; middle 

 coxae large, transverse, not prominent; posterior coxae flat, 

 transverse; anterior tibiae palmate, toothed, with a single 

 terminal spur; middle and posterior tibiae variable in form, 

 with two spurs, except in Coprini, where there is but a single 

 one; tarsi 5-jointed, the anterior ones sometimes wanting; 

 claws generally equal, rarely wanting, usually with an inter- 

 mediate bisetose onychium. 



A very large and distinctly limited family of insects, the mem- 

 bers of which exhibit great variations in the form and arrangement 

 of the various organs of the body, while preserving a character- 

 istic appearance, and, conjoined with it, the lamellate antennal 

 club and the fossorial legs. 



For reasons mentioned in the prefatory remarks to my synopsis 

 of the Melolontkidae of the United States,* I prefer dividing the 

 family into three sub-families, according to the position of the 

 abdominal spiracles. Erichson and Lacordaire establish but two 

 sub-families, while Burmeister arranges the genera in a totally 

 different manner. 



I. Abdominal spiracles situated in the membrane connecting the dorsal 

 and ventral corneous plates, the last one covered by the elytra. 

 Ligula always separate from the mentum ; (larvae with the lobes of 

 the maxillaa separate). Lapakosticti. 



II. Abdominal spiracles in part situated on the superior portions of the 

 ventral segments, the last one usually visible behind the elytra ; the 

 rows of spiracles feebly diverging. Ligula sometimes free, usually 

 connate with the mentum. Melolonthid^e. 



III. Abdominal spiracles (except the anterior ones) situated in the dorsal 

 portion of the ventral segments, forming rows which diverge strongly ; 

 last spiracle usually visible behind the elytra. Ligula always connate 

 with the mentum ; (larvae with the lobes of the maxillae connate). 



Pleukosticti. 



* Journ. Acad. Nat. Sci., 2d ser., iii. 225. 



