4 NatTuraL History BuLvetin. 
The ¢ of this insect was formerly described by Dr. Brendel 
under the name Decarthron cornutum, and the 9 as Lryaxis 
inornata. Afterwards finding them in large numbers with 
ants, he recognized them as sexes of one species. 
Plate IX, Fig. 74, 3; 75 9. Habitat. lowa. 
A second species of this genus was discovered by Mr. 
Schwarz, in Florida, and is thus far unknown to me. It is 
said to differ chiefly in the ankylosed antennal joints. 
ArtTuHMius, Leconte. 
Head quadrate, differently sculptured in the sexes. Anten- 
nz regular and straight in the Q, irregular in the ¢. Pro- 
thorax globose. Elytra much wider than long; abdomen 
short. The line of juncticn of the ventral and abdominal seg- 
ments is straight, not serrate as in Batrisus; first segment 
one-third as long as wide, with four basal impressions, not 
convex longitudinally but very much so laterally, margin 
broad but not retuse. Fourth segment longer than its neigh- 
bors, first ventral very long. Legs slender, the anterior in 
the ¢ dilated and armed with a strong tooth near the middle. 
ey 
A. GLOBICOLLISY Deep yellow. Length, 1.7 mm. 
FTead, sides without the eyes parallel, occiput elevated, ver- 
tex convex, two small fovez between the eyes, and two more 
behind the frontal tubercles. ‘T‘hese tubercles are oblique and 
prominent, the frontal margin is transverse and emarginate in 
the middle. Antenne with every joint of a different form and 
presenting a different appearance according to point from 
which it is seen. First and second joint cylindrical or obcon- 
ical; third small, obconical, geniculate with the second; fourth 
undefinable; fifth large, semi-spherical; sixth small and glob- 
ular; seventh subglobular, truncate, very large; eighth trans- 
verse, acute-ovate; ninth small, globular; tenth obovate; 
eleventh large, acutely ovate. Prothorax globular, with a 
straight flat transverse sulcus near the base, and at the base 
is a linear slightly elevated margin. /ytra twice as wide as 
