AMERICAN COMPONENTS OF THE TENTYRIIN^ 485 



short and reflexed, the median part broadly rounded anteriorly, 

 with its apex broadly sinuate and finely, obtusely pectinate, cover- 

 ing completely all the mouth-parts ; mentum rather large, flat, 

 slightly transverse, broadly truncate at apex, narrowed toward 

 base, exposing the maxillae but entirely covering the short and 

 extremely broad ligula, the palpi slender, the last joint of the max- 

 illary elongate-oval, as long as the two preceding combined ; basal 

 margin of the buccal cavity reflexed, the side-pieces acute and 

 prominent ; mandibles bifid at tip ; eyes completely divided, 

 coarselv faceted, the upper part elongate, sunken deeply between 

 the prominent lateral margin and a strong supra-orbital ridge, the 

 inferior part very small, consisting of three to five facets ; antennae 

 about as long as the head and half the prothorax, stout, compressed, 

 perfoliate, cylindric, the tenth joint a little larger, the eleventh 

 very small and partially within the apex of the tenth, clothed 

 throughout with elongate yellowish scales ; neck narrow, less than 

 half as wide as the head ; prothorax cordate, small, slightly elon- 

 gate as a rule ; scutellum triangular, scarcely passing the basal 

 declivity of the elytra, the latter not margined at base, costate, feebly 

 inflexed beneath ; prosternum well developed before the coxae and 

 slightly tumid along the middle, the intercoxal process constricted 

 anteriorly, expanding and deflexed behind ; metasternum shorter 

 than the first ventral, the episterna narrow, with the suture repre- 

 sented by a more or less impressed series of coarse punctures ; 

 abdomen convex, the first two sutures nearly straight, the third 

 strongly, the fourth less strongly, sinuate in even arc ; coxae globu- 

 lar, moderately separated, the posterior slightly wider than long ; 

 legs rather short, stout, the tai^si short and stout, longer and less 

 stout in the arjjiatzis group, the basal joint sometimes but little 

 longer than the second, the claws small, slender and arcuate. 

 Sonoran regions. [Type A. costipennis Lee] Araeoschizus 



A full diagnosis of this genus, also, is given herewith, because 

 its true affinities seem to have escaped LeConte, Lacordaire and 

 Horn, who compare it with Stenosis and not with Adelostoma. 



Araeoschizus Lee. 

 This genus is widely diffused throughout the Sonoran fauna 

 of our southwestern States and northern Mexico, from which 

 latter region a species was described by Mr. Champion, in the 

 " Biologia," under the name mexicanus ; the various species 

 occur under stones in very dry regions and are said to be very slug- 

 gish in their movements and sometimes found with ants. The 

 material in my cabinet appears to pertain to eleven species, 

 which may be recognized by the following descriptions : — 



Vestituie of the elytral ridges erect and bristling ; femora unarmed 

 throughout 2 



