20 TERTIARY RHYNCHOPHOROUS COLEOPTERA. 
half as long again as their greatest width, punctate like the prothorax, but 
the puncta here with a longitudinal arrangement, and besides each elytron 
has two rows of conspicuous punctate striae, one near the middle of the elytron 
fading apically, the other nearer the sutural margin than the median stria, 
and meeting next the tip of the elytron the apex of a slight submarginal 
ridge. 
Length of elytra, 2°75™". 
Roan mountains, western Colorado, from the most prolific insect bed, just 
beneath the topmost layers. Two specimens, Nos. 295, 303, U. S. Geologi- 
cal Survey. 
ISOTHEA (e/o@Oé@), gen. nov. 
The head in this genus is of exceptional length, being slightly longer 
than the rostrum, and with it two-thirds as long as the rest of the body; it 
tapers regularly, but with full sides, to the rostrum which is stout, fully one- 
fourth the breadth of the head. Antennz almost as long as the greatest 
width of the body, fully,a third longer than the beak, joints 1-2 subequal, 
slightly shorter and a little stouter than those succeeding, 3-5 longest, 6-8 
about half as long as 1-2, 9-11 large and broad, forming an open club, of 
which 9-10 are twice as broad at apex as at base, subtriangular and trun- 
cate, the terminal joint obovate. Eyes large, lateral, not very prominent. 
Legs somewhat shorter than in Rhynchites, but with identical form, includ- 
ing the tarsal joints, unless the penultimate joint is more deeply bilobate. 
Structure of elytra indeterminable. Third ventral segment of abdomen dis- 
tinctly shorter than the second. 
The form of the body in this genus is somewhat elongate but not par- 
allel-sided, showing a somewhat oval outline and being broadest in the 
middle of the abdomen. 
A single species occurs at Florissant. 
IsoTHEA ALLENI. 
Plo iw, Hie. 2 Pyne dy 
The specimen, admirably preserved in most of its details, lies upon its 
back, so that the sculpturing of the elytra can not be determined. The 
head is transversely and rather delicately striate, the strie turning some- 
