AMERICAN COLEOPTERA. 279 



exclude all the species of Ptilinus known to us except the Califor- 

 nian ramicornis, which Randall could by no possibility have found 

 in Maine. In both the LeConte and Horn collections are speci- 

 mens labeled thoracicus, and all have yellow antennae. Those so 

 named in the LeConte cabinet are probably the species here re- 

 garded as pruinosus Csy. ; the Horn specimens are lobatus Csy., if I 

 have properly interpreted the species. 



The species known to me separate as follows : 



Elytra feebly but regularly striate-punctate, antennal rami very slender and 

 much longer than the prothorax • • • b'. 



Elytra not at all striate, the punctures not serial in arrangement, except in % of 

 acuminatus ; antennal rami never as long as the prothorax 2. 



2. Side margin of prothorax fine but well defined and even throughout, subapi- 



cal transverse carina of last ventral segment distinct in both sexes. ..3. 



Side margin of prothorax irregularly grannlato-serrate, and not very well 



defined ; subapical ventral carina nearly or entirely wanting in both 



sexes 5. 



3. Antennal rami longer, that of the third joint about twice the length of the 



joint, that of the fourth joiut six or seven times the length of the 



joint (Eastern U. S.) 1. ruficoniis. 



Antennal rami shorter, that of the third joint subequal in length to the joint 

 itself (Pacific Coast) 4. 



4. Elytral punctuation confused and distinct from base to apex in both sexes; 



prothorax in the female sinuate at the sides subapically, the median 



lobe distinctly serrulate 2. basalis. 



Elytral punctuation subserial in arrangement in the male; very fine, and dis- 

 tinct only toward the base in the female; prothorax in the latter sex 

 arcuately oblique subapically, the apex angulate and slightly promi- 

 nent, not at all serrulate 3. acuminatum. 



5. Ramus of fourth antennal joint scarcely three times the length of the joint; 



prothorax subequal to the elytra in width- ■ • 4. lobatus. 



Ramus of fourth joint nearly five times the length of the joint; prothorax a 

 little narrower than the elytra 5. pruinosus. 



6. Prothorax broadly evenly arcuate at apex, feebly sinuate at middle, subapical 



ventral carina wanting in both sexes 6. raniicornis. 



1. P. ruficoniis Say. — Male. Cylindrical, elytra not wider than the pro- 

 thorax ; black or piceous, opaque, antennse and legs rufotestaceous, the thighs 

 sometimes darker ; pubescence exceedingly short, fine, and perfectly recumbent. 

 Head evenly convex, moderately densely gran u lose; eyes separated by rather 

 more than twice their longest diameter. Antenna' strongly flabellate. the ramus 

 of the third joint about twice (more or less,) as long as the joint; that of the 

 fourth joint six or seven times as long as the joint. Prothorax slightly wider 

 than long, widest before the base, sides broadly arcuate, apex narrower than the 

 base; side margin very narrow, not obviously wider at the hind angles, scarcely 

 at all serrulate, though sometimes a trifle irregular; hind angles rounded, front 

 angles right, apical margin moderately strongly rounded, narrowly reflexed at 



TEANS. AM. ENT. SOC. XXXI. JULY, 1905. 



