SCARAB^IDAE. 261 



sexes ; hind tibiae digitate or truncate at tip, not expanded; first 

 joint of hind tarsi elevated ; stridulating organs on the inner 

 surface of tlie elytra, along the lateral margin. 



In Phileurus the mcntum is of moderate size, oval, slightly 

 emarginate in front, and the first joint of the hind tarsi is pro- 

 longed into a spine at the extremity. 



Four species are known in our fauna, one of which, P. nalgvs, 

 is also found in South America; of the others, P. truncatus in- 

 habits tlie Southern States, P. cHbrosua Texas, and P. Hiatus 

 California and Arizona. 



Tribe III.— CETO]VIIi\I. 



In addition to the conical prominent anterior coxfe, this tribe 

 is distinguished by the occurrence in it of certain peculiarities 

 not found at all, or only exceptionally, in the other tribes of 

 Pleurosticti, 



In the majority of genera the mandibles are feebly developed, 

 and in great part membranous; they and the labrum are always 

 under the clypeus ; the antenniB are always lU-jointed, with 8- 

 jointed club; the internal lobe of the miixillse is obsolete; the 

 elytra do not cover the pygidium, and the epipleurte are not 

 distinct; the side pieces of the mesothorax are large, and ascend 

 between the thorax and base of the elytra so as to be usually 

 visible from above ; the last pair of spiracles is situated on the 

 suture between the connate fifth ventral and propygidium, but is 

 variable in position, being sometimes near the posterior margin, 

 sometimes near the anterior one; the claws are always equal and 

 simple, with a distinct onychiura, which, however, is very small 

 in Cremastochilus ; the ventral segments are six, not connate, 

 although very slightly movable ; the mesosternum is usually 

 prominent between the coxae; the side pieces of the metathorax 

 are variable in size, but the epimera are always visible. Tlu; 

 genuine Cetonije, in flying, do not raise or expand the elytra, as 

 most Coleoptera do, but pass the wing out from the side, under 

 the elytra, which do not at all embrace the sides of the body. 



Both sub-tribes are found in our fauna: — 



Epimera of the mesothorax visible from aljove. Cetomini. 



Epimera of the mesothorax not visible froin above. Tkichiini. 



