1878.] 551 {Horn. 
transverse series; behind these the thorax is densely and coarsely punc- 
tured, disc sub-carinate at middle posteriorly, and on each side of this a 
feeble depression. Elytra cylindrical, obtusely declivous posteriorly, sur- 
face coarsely and deeply and moderately densely punctured. Body be- 
neath piceous, legs paler. Length .12 inch; 3 mm. 
This species differs from all the others by its eleven-jointed antenne, the 
additional joint occurring among the small ones between the second and 
the club. Its form is also shorter, and more robust, resembling in this re- 
spect some of the species of Xyleborus. In this species we have the third 
instance in our fauna of the variation of the number of antennal joints 
within what must be considered generic limits. 
Several specimens sent me by Dr. Summers from New Orleans. 
“Tribe PSOUNE. 
Head entirely free, eyes at least moderately prominent. Antenne nine 
or ten-jointed, terminated by three-jointed club, which is a little shorter 
than the preceding portion. Thorax oval, sides not margined, surface not 
muricate. Tarsi slender, elongate, four-jointed in Psoa, five-jointed in 
Polycaon, the first joint being very small. 
Two genera occur in our fauna. , 
Anterior coxee separated, tibise serrulate......................Polycaon. 
Anterior cox contiguous, tibie slender, simple...................-Psoa. 
With Polycaon I have united Hvropioides, the ten-jointed antenne being 
the only differential character. There are species belonging to the latter 
genus with the declivity margined, but not exactly as in the normal 
series of Polyeaon. Acrepis does not differ essentially from Psoa, and 
another instance is thus presented of the analogy of the fauna of the west- 
ern side of our own continent, with that of the western side of the eastern 
continent. 
POLYCAON Lap. 
This genus contains species of moderate size, the first black and slightly 
depressed, the others piceous or brownish and cylindrical. 
The antenne exhibit important differences. In Sfowtit the fourth joint 
is rather elongate, and 4-8 slightly compressed, these taken together longer 
than the club. In the other species the third and fourth joints are of 
nearly equal size, and sub-moniliform, and taken together not longer, rarely 
as long as the club. 
Ezxopioides (which is here suppressed) differs only in having one joint 
less in the funiculus. 
The prosternum separates moderately widely the coxe, and is slightly 
dilated behind in Stowfiz, or not dilated in the others. 
The elytral declivity presents two forms, that in which the tip is gradu- 
ally declivous, or that in which the declivity is more or less flattened, and 
limited by an acute edge, thus far an equal number of species occurs in 
each. 
