THE GENUS DENDROCTONUS. ( 



has three to four closely connected joints defined by curved lines. 

 The front of the head has a distinct middle elevation toward the 

 base of the mandibles, called the epistomal process (see figs. 2, 3). 

 The pronotum is slightly more than half to slightly less than half 

 as long as the elytra, which have fine to coarse rugosities between 

 rows of obscure to distinct punctures. 



The diagram, Plate I, gives the technical and common names of 

 the beetles of the genus, and shows how the different species fall into 

 natural primary and minor divisions according to certain structural 

 characters and peculiar habits. 



ADULT CHARACTERS. 



In the species of Division I the pronotum is somewhat elongate and 

 as broad as the elytra, and in those of Division II the pronotum is 

 shorter and is usually narrower than the elytra. 



In species 1 to 8 (subdivision A) the body is somewhat slender, 

 and the pronotum is but slightly narrowed toward the head, which 

 in all but species 3 (comprising subsection h 1 ) has a frontal groove 

 and two frontal elevations. In species 1 and 2 (section a 1 ) the elytra 

 are without long hairs, while in species 3 to 8 (section a 2 ) there are 

 long hairs toward and on f;he declivity. 



In species 9 to 11 (subdivision B) the body is stouter and the 

 pronotum is distinctly narrowed toward the head, which is without 

 frontal groove or elevations. In species 9 and 10 the punctures of 

 the pronotum are moderately coarse and deep, while in species 11 

 they are shallow and usually fine, with the surface more shining. 



In species 12 to 21 (subdivision C) the punctures of the pronotum 

 are of irregular size, while in species 22 and 23 (subdivision D) 

 they are regular. 



In species 12 and 13 (section a 3 ) the striae of the elytral declivity 

 are deeply impressed, and the interspaces are convex, while in 

 species 14 to 21 (section a 4 ) the striae are but slightly or not at all 

 impressed and the interspaces are flat or but slightly convex. In 

 species 14 to 19 the striae of the elytral declivity have obscure to 

 fine punctures, while in species 20 and 21 the strial punctures are 

 coarse and distinct. Species 22 and 23 are easily distinguished by 

 their large size, evenly punctured pronotum, which is subelongate and 

 almost as broad as the elytra, and by the very large and prominent 

 head. 



EXTERNAL SEXUAL CHARACTERS. 



In species 1 to 8 (subdivision A) the females are distinguished by 

 a transverse, rather broad, elevated ridge across the pronotum near 

 the anterior margin, moderately broad head, and moderately large 

 mandibles. The males are without the transverse ridge across the 



