io MEMOIRS ON THE COLEOPTERA 



elongate, convex, more shining than in the preceding section; head 

 distinctly narrower than the prothorax, rugulose, the oblique im- 

 pressions deep, the intermediate surface broadly smooth and with 

 fine scattered punctures; prothorax well developed, slightly wider 

 than long, the sides converging and very evenly, moderately arcuate 

 from apex to base, the latter broadly lobed medially; side margins 

 acute but much more finely and feebly reflexed than in the pre- 

 ceding section; surface with anastomosing fine sculpture, stronger 

 laterally, feeble on the broadly flattened median part, which is more 

 rapidly declivous at the sides to the transverse impression; elytra 

 barely more than one-half longer than wide, the sides evenly arcuate, 

 rather rapidly pointed at apex; surface somewhat uneven, with 

 strong, rather close-set punctures and distinct foveae. Length (9 ) 



15.5 mm.; width 5.4 mm. Oregon borealis Csy. 



A Similar but somewhat larger and a little more elongate, the 

 punctures of the very smooth polished medio-frontal surface fine 

 and barely evident; prothorax perfectly similar throughout, 

 except that the rugulosity is slightly finer and feebler and the 

 median flattened part is better defined posteriorly by the rather 

 more abrupt slopes; median stria sometimes slightly deeper 

 centrally a reversion toward Megomus; elytra similar and 

 widest at the middle, with evenly rounded sides but more elongate 

 and not quite so convex, two-thirds longer than wide; punctures 

 small and widely separated medially, stronger and closer laterally. 

 Length (cf) 17.0 mm.; width 6.0 mm. California (Plumas Co.), 



Nunenmacher pronotalis W. Horn 



B Similar to pronotalis but a little narrower, more convex and still 

 more shining, the front similar, the punctulation almost completely 

 obsolete though traceable; prothorax throughout as in borealis 

 but rather strongly and more evenly, vermicularly rugulose 

 throughout, the postero-median flattened part less well defined 

 than in pronotalis but better defined than in borealis; base trans- 

 verse, barely at all lobed medially; elytra nearly three-fourths 

 longer than wide, very evenly oval, with evenly arcuate sides, the 

 surface convex, the punctures fine and sparse suturally, a little 

 less fine and less sparse laterally, the foveae small but distinct. 

 Length (cf) 16.5 mm.; width 5.5 mm. California (Lassen Co.), 

 Nunenmacher nunenmacheri W. Horn 



The copulatory spicule, so far as exposed in examples of this 

 group at hand, is very slender and strongly bent arcuately down- 

 ward at tip, very much as in the preceding group, but I have not 

 been able to note its conformation in the singular borealis section, 

 which is of more northern distribution and quite distinct in several 

 directions besides the postero-medial flattening of the pronotal 

 surface, which is barely traceable in borealis, feeble in nunenmacheri 

 and somewhat pronounced in pronotalis. 



