THE GENUS DENDROCTONUS. 39 



indicated in the wall of the coxal cavity. Sternites 4, 5, and 6 are 

 nearly of equal length, while sternite 7 is nearly as long as 5 and 6 

 together, with the posterior margin broadly curved and forming 

 the apex of the exposed series. Sternite 8 (figs. 23, C, and 24, D) is 

 entirely covered by 7, and is represented in the male by a narrow 

 chitinous rim below the anal opening, while in the female the median 

 section of this sternite is membranous. 



Suture 3, between sternites 3 and 4, is the first visible suture, and 

 is rigid and straight throughout, while sutures 4, 5, and 6 are slightly 

 flexible and are strongly recurved toward and between the hypo- 

 pleurites, thus presenting an important generic character. 



SPIRACLES. 



There are 9 well-developed spiracles, 2 thoracic and 7 abdominal, 

 with the rudiments of a tenth. The large mesothoracic spiracle is 

 located in the intersegmental membrane between the prothorax and 

 mesothorax, and lies between the preepisternal process and the 

 anterior ventral angle of the preepisternum. It overlaps the anterior 

 margin of the latter for half its length, but is completely covered and 

 obscured by the epimeral area of the prothorax. The metathoracic 

 spiracle is situated in the intersegmental membrane between the 

 metathorax and mesothorax, and concealed beneath the dorsal 

 margin of the mesepimerum. The abdominal spiracles 1-7 are con- 

 spicuous; 1 is very large and situated in the epipleurite just posterior 

 to the pleural hook of the metapostscutellum; 2-7 are situated in 

 their respective epipleurites, as shown in figures 3, 22, 23, and 24, while 

 8 is evident, but rudimentary. 



THE LEGS. 



The structures and characters of the parts of the legs are so well 

 illustrated in the figures (figs. 3, 26-29) that they do not require 

 detailed description. The procoxae and mesocoxae are large, globose, 

 and prominent, the former subcoritiguous and the latter widely 

 separated by the elevated intercoxal or sternellar piece, while the 

 metacoxae are oblong, oval, and separated by the process of the 

 third abdominal sternite. There is no striking difference in the 

 anterior, middle, and posterior trochanters, femora, tibiae, and 

 tarsi. The trochanters are small; the femora are moderately stout, 

 and each is as long as its tibia, which is dilated toward the apex and 

 armed on its outer lateral margin with stout teeth. The anterior 

 dorsal area has a distinct tarsal groove for the retractile tarsus, as 

 shown in figures 26 to 29. The tarsi are each more than half as long 

 as their tibiae, and have five joints; joint 1 is always longer than 2, 

 but never as long as 2 and 3 together; 3 is distinctly bilobed, the 



