158 PROCEEDINGS OF THE NATIONAL MUSEUM vol.87 



second specimen does not agree with it and since he does not mention 

 the other locaUties. 



LeConte gave as the distinguishing mark of this species the promi- 

 nent posterior angles of the prothorax, a character that is usually pro- 

 nounced in this species. This prominence of the basal angles is due 

 primarily to the width of the prothorax, coupled with the unusually 

 well developed tooth and the deep incurvation below the tooth on the 

 basal margin. The prothorax is wider than in many species, being 

 nearly twice as wide as long, and covered with short appressed pubes- 

 cence. It is somewhat irregularly depressed on the sides both at the 

 base and apex. The elytra are broadly oblong, with a short intra- 

 humeral depression, but this is not so long or so pronounced as in 

 guttulata or conspuia, and the punctation is not so shallow as in those 

 two species. The pubescence, shorter than in guttulata, differs also 

 in being fine and closely appressed. The apical joints of the antennae 

 are usually stouter than in any other species of Monoxia. Besides 

 having rather prominent basal angles of the prothorax, it is still fur- 

 ther distinguished by being one of the largest species, the length 

 ranging from 4.5 to 5.3 mm. and the width from 2 to 2.5 mm. It is 

 much larger than consputa with which Horn synonymized it. The 

 aedeagus is longer than that of any of the other large western species 

 except M. grisea, which has a thicker and heavier aedeagus. The 

 aedeagus of angularis resembles somewhafthat of M. batisii Blatchley, 

 a quite diiferent species occurring in Texas and Florida. 



As in both M. consputa and M. sordida, there appear to be various 

 closely related forms or races of angularis from different localities. 

 Along the Pacific coast, from California to British Columbia, the 

 specimens have rather scanty, closely appressed, and inconspicuous 

 elytral pubescence with the punctation beneath distinctly visible. 

 Specimens from eastern Washington (Elk, Pullman, Ritzville), on 

 the other hand, have moderately dense elytral pubescence, and the 

 prothorax is not so depressed on the sides. Specimens from Idaho, 

 Montana, Wyoming, Utah, and Colorado have still denser elytral 

 pubescence, which almost conceals the punctation beneath. In these 

 the prothorax appears wider and less depressed on the sides, with the 

 basal angles more prominent. In all the specimens examined from 

 various localities, the aedeagus is similar in being long, curved, and 

 slender. The tip, however, in specimens from eastern Washington, 

 Idaho, Montana, Utah, and Colorado is wider than in specimens from 

 the Pacific coast and somewhat wedge-shaped. It is possible that 

 with fuller laiowledge of their biology, the specimens from the eastern 

 part of its range may prove to represent one or more distinguishable 

 subspecies. 



M. angularis is one of the most abundant species of the genus 

 throughout the Pacific and northwestern States, but apparently does 



