PKELIMIiSrAKY CLASSIFICATION OF SCOLYTOIDEA. 179 



LEGS. 



There is a wide range of variation in the form, color, sculpture, and 

 relative proportions of the coxa, trochanter, tibia, and tarsus of the 

 anterior, median, and posterior legs. (Part I, figs. 1, 3, 26-29. ^'^ 

 The anterior tibia and tarsus are of special taxonomic importance in 

 distinguisliing the primary and secondary divisions of the superf amily 

 and, to a less extent, m distinguishing the primary or minor groups of 

 the families, subfamilies, and genera. (Pis. X, XIII-X^T.) The 

 variation in the tibia is from a simple, compressed, slightly dilated 

 form vrith the outer margin serrate, as in Hypothenemus, to a short, 

 broad form with parallel, smooth margins, as in Micracis and Scolytus, 

 or broader at the base, as in Wehhia and Hypohorus, and to extreme 

 and odd forms as m Platypus. The character of the ve'stiture usually 

 conforms to that of the body, such as scales, barbed hairs, and simple 

 hairs, varying in distribution and density on the ventral and dorsal areas 

 and the margins. The sculpture ranges from smooth to imbricate 

 and from irregular rugosities to promhient ridges, the latter reaching 

 a maximum development m Platypodid^. The tarsi vary in form 

 from slender to stout and the joints in relative lengths, widths, and 

 vestiture. The third jomt varies from simple to emarginate and 

 deeply bilobed, \\atli the ventral surf ace ranging from nearly glabrous 

 to pubescent and to densely padded, which latter extreme is found m 

 Plil(]e,oborv,s . 



ELYTRA. 



The elytra, or anterior wings, are exceedingly variable in form, 

 vestiture, and sculpture, rangmg from the simple types with scales, 

 fine punctures, and obscure striae which are not impressed, as in 

 Hypothenemus, to the forms with hairs and with distinctly impressed 

 stride and elevated interspaces, the latter with rugosities and rows of 

 punctures or smooth and without punctures; the base from plain to 

 strongly elevated and serrate; the sides from parallel to converging 

 posteriorly or strongly rounded; the dorsal area from flat and straight 

 to convex and strongly rounded from base to apex; the dechvity 

 from plain, steep, and convex to retuse or armed and strongly obUque 

 from base to apex, and the side margins from serrate to straight or 

 emarginate. With all of these almost endless variations and their 

 different combmations cf elements there is available a profusion of 

 characters for the definition of groups of genera and species. 



POSTERIOR WIXGS. 



The true functional wings, as pointed out by Niisslin (1911), are 

 quite variable in form, proportions, and character of the venation 

 and represent two specified types, one with and the other without 



a Figiu'es 26-29, Pai't I, represent the reverse faces of the right instead of the left 

 tibia, a mistake which was uniortiinately overlooked in the manuscript and proofs. 



