190 MEMOIRS ON THE COLEOPTERA 



The difference between the tripunctate and unipunctate condi- 

 tion near the thoracic base, is not always clear, but fortunately it 

 serves unequivocally in separating species of the incurva and nebu- 

 losa subsections, which otherwise would be difficult to treat, be- 

 cause of the many species and lack of striking structural modifi- 

 cation. 



The species described by the writer many years ago under the 

 name Barytachys gemellus, was united with fuscicornis Chd., by 

 Mr. Hayward, but improperly I think ; fuscicornis, from Louisiana, 

 seems to be very much larger, being, according to Chaudoir, 2.5 

 mm. in length. 



The two forms laxipennis and famelica are represented only 

 by single specimens, having the general structural characters of 

 xanthopus and. found in the same locality; although differing 

 markedly on cursory comparison, it would therefore be injudi- 

 cious to assign more than subordinate value to them for the pres- 

 ent. Xanthopus is a very small species, the length given by De- 

 jean being 1.5 mm. That author, however, was very apt to under- 

 estimate the length, as LeConte was to overestimate, depending 

 entirely upon methods of measurement, the former author evi- 

 dently holding the insect below the scale and the latter above. 

 There can be but little doubt that the name mendax was applied 

 by LeConte to the form named xanthopus by Dejean, and that 

 the xanthopus of LeConte is the larger, wholly deep black species 

 named levipes in the above table. 



The three species rubricauda, gaudens andfracta are undoubtedly 

 closely interrelated. The first is the largest and rather the stout- 

 est and has only two of the elytral striae distinct, though one or two 

 others are feebly traceable by careful search. Gaudens has five 

 striae visible, the first three conspicuous; it is a little smaller and 

 rather less stout than rubricauda, and has a much greater develop- 

 ment of the bright rufous subapical coloring of the elytra; it seems, 

 also, to be peculiar to the Rio Grande Valley. Fracta is the small- 

 est and narrowest and is one of the more diminutive forms of the 

 genus; it inhabits the interior regions of Texas, more especially to 

 the westward of the extended Mississippi Valley regions occupied 

 by rubricauda. These were all confounded with xanthopus by Mr. 

 Hayward, who at the same time called attention to the diversi- 



