108 AMERICAN ENTOMOLOGY. 



elytra dark bluish-green, or somewhat violaceous ; middle of the 

 lateral edge obsoletely piceous : postpectus and feet deep black : 

 venter testaceous. 



Variety, a. Elytra blue ; venter and thorax sanguineous. 



Obs. This species was taken on the Mississippi, and specimens 

 also occurred near the Rocky Mountains. It is as large as M. 

 4-maculafus Fabr., and larger than M. thoracicus Fabr., which 

 it much resembles. The variety was sent me from Massachu- 

 setts by Mr. Charles Pickering. 



The right figure of the plate. 



[Also a Collops. — Lec] 



Malachius nigriceps. — Specific character. Thorax rufous, 

 with a large black spot : elytra blue : venter sanguineous. 



M. nigriceps nobis, Jour. Acad. Nat. Sci. vol. iii. p. 183. 



Desc. Head deep black, pale testaceous or rufous before : tho- 

 rax rufous, with a large black spot, sometimes composed of two 

 dilated, confluent ones, and not attaining the anterior margin : 

 elytra violaceous, blue, or greenish ; pectus rufous, at the origin 

 of the feet black : postpectus black : feet black : thighs sometimes 

 rufous, particularly the anterior ones : venter sanguineous. 



Variety, a. Thorax entirely black. 



Obs. Distinguishable from the tricolor by the black spot of 

 the thorax, and by the proportion of this part, which is compa- 

 ratively longer than in that insect. Its antennas present the re- 

 markable character of the dilatation and irregularity of the 

 second joint of the antennas. 



The upper middle figure of the plate. 



[Also a Collops ; the form of the second joint of the antennas 

 mentioned is peculiar to the male. — Lec] 



Malachius vittatus. — Specific character. Thorax rufous, 

 with a large black spot: elytra blue, margin and suture rufous. 



M. vittatus nobis, Jour. Acad. Nat. Sci. vol. iii. p. 181. 



Desc. Head black ; labrum and base of the antennas rufous : 

 thorax rufous, with a dorsal black spot composed of two confluent 

 ones, not reaching the anterior margin : elytra bright greenish- 

 blue : exterior margin, suture, and tip rufous ; this color is a 

 little dilated behind the humerus ; pectus rufous ; about the base of 

 the feet black : postpectus and venter black, incisures of the 



