DYNASTIISLE 263 



Length (cf) 32.0-38.0 mm., (9) 30.0 mm.; width (cf) 18.3-20.0, 

 (9) 16.7 mm. Lower California (Santa Rosa). [Megasoma thersites 

 Lee.] thersites Lee. 



I know nothing concerning the life habits or food plant of this 

 remarkable species, of which a full resume of characters is given 

 above, as it has never been adequately described; it will be noted 

 that the differences between the male and female are parallel to 

 those distinguishing the sexes in elephas, which is the only other 

 species of the Megasoma group inhabiting the continent of North 

 America. 



Tribe PHILEURINI. 



The general habitus of the numerous genera and species in this 

 tribe is quite distinct from that of any other Dynastid group and 

 recalls the Passalidae in many external features and, as in the 

 Passalids, the cephalic and pronotal horns and tubercles are fre- 

 quently not more than very slightly different sexually; in addition 

 to this peculiarity of facies and sexual constancy, the labial palpi 

 are inserted on the under surface of the ligular plate, in a manner 

 different from that occurring elsewhere in the subfamily; so, alto- 

 gether, it can be said without much risk of contradiction, that the 

 Phileurini are the most isolated section of the Dynastinee; they do 

 not seem to be Dynastids at all, in fact, and might constitute a 

 distinct subfamily. The body is generally oblong, unusually de- 

 pressed- again as in the Passalids and the result of similar life 

 habits in all probability, with very thick and dense, generally 

 polished, black and strongly sculptured subglabrous integuments, 

 and the head is generally bicorniculate or bituberculate, though 

 quite different in the remarkable Phileurus cribrosus of LeConte, 

 which has recently and very justly been made the type of a distinct 

 genus. We have two genera as follows : 



Hind tibiae obliquely spiniform externally at apex; head with two pos- 

 teriorly diverging ridges, sometimes subobliterated by the corniform 

 processes, never with transverse ridge; second strial interval of the 

 elytra broader basally and bearing detached punctures, sometimes 

 however very few in number or accidentally wanting; body more 

 elongate-oblong in form. [Type Scarabceus didymus Linn.] 



Phileurus 



Hind tibiae not obliquely spiniform externally at tip; head without tu- 

 bercles but having a transverse ridge at the base of the clypeus; 

 strial intervals of the elytra equal among themselves, the second 



