74 MEMOIRS ON THE COLEOPTERA 



as species of a single genus in our fauna, are for the most part in 

 actuality so many generic or quasi-subgeneric types, the real 

 species and subspecies being, as a general rule, these so-called erratic 

 variations. The complete proof of this is certainly to be seen in 

 manifold instances in the material now in hand, and, among other 

 things, it proves some of the early conceptions of our predecessors, 

 such as the taking on or loss of granules and other permanent modi- 

 fications of the chitinous exoskeleton, or the transformation of one 

 widely distinct species into another, as a consequence respectively 

 of seasonal change or through stages of true variation (Horn Rev. 

 Ten., pp. 284, 287, under Asida actuosa and A. captiosa; also, 

 recently, Proc. Cal. Acad. Sci., ser. 2, IV, p. 345 under Edrotes) 

 to be visionary and unwarrantable. 



In accordance with the observations and reasoning above stated, 

 I here suggest the following scheme of genera of the tribe Asidini, 

 so far as known to me at present, those which are foreign to America 

 being indicated by the asterisk. Under the apparently prevailing 

 opinion of systematists regarding generic and specific weight in 

 the Coleoptera, most of them will probably be held to be rather sub- 

 genera than genera and in a very few cases this may quite possibly 

 be true, but the large majority of them are, in the opinion of the 

 writer, as definite as those now acknowledged by general consensus 

 to be valid in almost any other section of the Tenebrionidse: 



Coxce more or less widely separated. North America 2 



Coxae more or less narrowly separated, always notably more approximate 

 than in the preceding section. Palaearctic faunal regions, including 

 northern Africa 21 



2 Mentum entirely filling the buccal opening and without trace of 

 pedestal: body generally coated densely with earthy matter 3 



Mentum not entirely filling the buccal opening and always placed upon 

 a more or less evident pedestal formed by a gular prolongation 4 



3 Mentum covering completely all the month-parts, fitted closely to 

 the sides of the opening and contiguous to the mandibles when 

 closed; trochantin wanting; sculpture of the elytra very rough and 

 uneven; prosternum porrect and obtuse between the coxae. [Type 

 A. contortits Lee.] Astrotus 



Mentum closely fitted to the sides of the buccal opening, completely 

 concealing the ligula and nearly or quite attaining the closed mandi- 

 bles; elytra with straight and fine dorsal ridges and side margin; 

 prosternum deflexed posteriorly. [Type S. graciliformis Sol.]. 



Stenosides 



4 Ligula small, generally flat, angularly emarginate to subtruncate 



