300 COLEOPTERA OF NORTH AMERICA. 



the hind tarsi, which are comparatively wider in T. annulaium. 

 Variations in the proportions of the joints of the hind tar.si are 

 not unusual in Cerambycidte, as, for instance, in Criocephalus. 

 This fajt has induced us to refer Sphsenolhecus cyaiiicoUis to 

 Entoiuosterna, instead of forming of it the new genus indicated 

 but not named by Lacordaire. * 



Of the genera tabulated above Stenaspis and Tragidion occur 

 from the Atlantic to the Pacific in the warmer regions, the former 

 extending northward in the central region, the latter in the 

 Atlantic district. Purpuricenus occurs in the middle and 

 Western States. The next three genera are found in Texas, 

 and Batyle occurs in the Atlantic region especially southward. 



The genus last named is placed by Lacordaire in Heteropsides, 

 of which he observes that the middle coxal cavities are closed 

 externally; we find, however, in our specimens that the mesotho- 

 racic epimera attain the coxal cavities, and that they are as open 

 as in Purpuricenus. The character as used by Lacordaire seems 

 very deceptive, and vv'ithout value for systematic results. 



Group IV. — Tyloses. 



Closely related to the preceding, and only differing in fact by 

 the mandibles not- being acute at tip, but truncate, forming a 

 chisel-shaped edge, which is emarginate. The front is moderate 

 in size, nearly perpendicular, and the antennal tubercles are not 

 much elevated ; the gence are not elongated. The scutellura is 

 small, acutely triangular, and the stridulating plate of the meso- 

 notum is large. The side pieces of the metasternum are tolera- 

 bly wide, not narrowed behind, and the scent pores are distinct, 

 except in Perarthrus viltalus and Sphcenothecu.s hivitlatuH. 'V\\v, 

 legs are slender, thighs not clavate, tibial spurs rather long, hind 

 tarsi with the 1st joint equal to the two following; less slender 

 in Tylosis and Crossidius than in the other genera. The antenntB 

 are slender, with elongate sensitive spaces near the carina of the- 

 under margin. The last joint of the palpi is subcylindrical, and 

 impressed, as usual, in the other groups of this tribe. 



Our genera, which are found mostly in Texas, Arizona, and 

 liower California (Crossidius alone extending into Colorado, 

 California, and Oregon), may be tabulated thus: — 



* Gen. Col. ix. 184, note 3. 



I 



