68 TERTIARY COLEOPTERA OF NORTH AMERICA. 



This species, on account of the excessive brevity of the thorax as well 

 as of the anteimge (which, notwithstanding the shortness of the thorax, do not 

 reach its hinder edge) can hardly be compared with any of our modern forms. 



Length, 5 to fi mm.; bi'eadth, 1.25 to 1.5 mm. 



Florissant, Colorado; three specimens, Nos. 3736, 6930, 9207. 



BOLETOBIUS STYGIS Sp. nOV. 



PI. VIII, %. 7. 



Head less than half as long again as broad, with nearly straight and 

 converging sides, smooth, piceous. Antennae reaching back almost to the 

 base of the thorax, very gradually enlarging from the fifth joint apically, 

 these joints stout, subquadrate, dark luteous, hairy, the fifth and sixth joints 

 slightly longer than broad, the seventh to tenth of nearly equal length and 

 breadth, scarcely cuneiform, the last largest and ovate, one-third as long again 

 as broad (the basal joints not preserved). Thorax longer than the head, 

 but apparently broader at base than long, tapering regularly from base to 

 tip, the latter being as broad as the head, the disk smooth, shining, luteous. 

 Elytra apparentl)^ of same width as the base of the thorax, longer than 

 head and thorax, piceous. Abdomen not so long as the rest of the body, 

 as broad at base as the elytra, narrowing at first slightly, on the apical half 

 more rapidly, to a somewhat pointed apex, the surface blackish testaceous, 

 with some bristly hairs. 



This is the smallest of the Florissant species and about as small as any 

 of our living American species; it differs from all I have seen in the char- 

 acter of the antennae, and like B. durabilis, to which of the Florissant sj^ecies 

 it is most nearly allied, has a very short thorax, though not of such excessive 

 proportions as there. 



Length, 3.25 mm. 



Florissant, Colorado; one specimen. No. 5397. 



MYCETOPORUS Mannerheim. 



A north temperate genus, tolerably rich in species, of which more than 

 half a d ozen occur in the United States. The only fossil species described 

 is the one here given from Colorado, but the genus has been recognized in 

 amber. 



