20 PROC. ENT. SOC. WASH., VOL. 24, NO. 1, JAN., 1922 



in two planes, a lateral and a dorsal. The lateral plane is very 

 narrow and elongate anteriorly, widening behind to form a 

 rough parallelogram. On the dorsal plane is a distinctly semi- 

 chitinized subtriangular. plate the posterior corner of which is 

 separated by a suture from the rest of the plate. The rest of 

 the dorsal area of the epimeron is membranous except for its 

 anterior portion which is semi-chitinous along its outer margin 

 where it fuses with the tergo-pleural membrane, gradually 

 becoming more strongly chitinized anteriorly until it ends in 

 the wing process (WP, fig. 20). 



The coxae of the metathorax (Cx3, fig. 17) are flat throughout 

 the genus, strongly transverse, gradually narrowed outward, 

 and separated along their inner margin. The posterior margin 

 is sulcate or strongly excavate for the reception of the femora. 



The legs of Melanotus are not remarkable. The pectination 

 of the claws is characteristic of the genus; while two other 

 Elateroid genera in America have pectinate claws (Eniconyx 

 and Aptopus}, they are not easily confused with Melanotus. 

 There is considerable variation in the number and character 

 of the pectinations in Melanotus, but as Candeze has said, not 

 only does the pectination vary in the same species and in the 

 same individual, but even in the two claws of the same tarsus. 



The elytron throughout the genus bears nine striae. It is 

 strongly deflexed along its anterior third and at the humeral 

 angle. The disc is flat to feebly convex anteriorly, depending 

 on the species, and distinctly convex posteriorly. The outer 

 margins of the elytra of the females are subparallel to their 

 middle or posterior third, depending on the species, and thence 

 narrowed to the apex; in the males the elytra are narrowed 

 from the humeral angle or, in other species, from their anterior 

 third, to -the apex. The striations vary in form and depth 

 with the species; they are sometimes posteriorly (cribricollis 

 Cand.) or laterally (paradoxus Melsheimer) obsolete. The 

 interstrial spaces are flat or convex, and vary from finely and 

 sparsely (angustatus Erichson) to very coarsely (tenax Say and 

 dijficilis Blatchley) punctate. The anterior margin of the ely- 

 tron is transverse and sinuate with often a more or less prom- 

 inent knob at the base of the fourth stria. The anterior margin 

 of the elytra is always deeply emarginate to receive the scu- 

 tellum. The humeral angle is strongly carinate in some 

 species. The elytra are conjointly and acutely rounded and 

 in a few species (e. g., scrobicollis Leconte) the tip of each elytron 

 is sometimes faintly acuminate. 



The wing (fig. 21) is of the Cantharoidean type as charac- 

 terized by Gahan (The Entomologist, v. 44, p. 121, 1911), 

 having the anterior branch of the media and the posterior 

 branch of the radius hooked so as to look like recurrent branches 

 of their respective veins. The second anal vein crosses and 

 interrupts the first anal vein throughout the genus. 



