AMERICAN COMPONENTS OF THE TENTYRIIN^ 467 



long as wide, very sparsely, simply and i-ather coarsely punc- 

 tate, becoming very coarsely and more closely so near the 

 sides anteriorly, the sides and basal margin as in elongatus^ the 

 sides before the feeble prominence straight for a longer distance 

 anteriorly ; scutellum subobsolete ; elytra equal in width to the 

 prothorax and three-fourths longer, twice as long as wide, the 

 surface almost perfectly smooth, with even series of widely 

 spaced double punctures which are moderate in size, the close-set 

 pairs of punctures arranged longitudinally, the intervals with 

 single series of very remotely spaced solitary punctures, which are 

 but little smaller in size; prosternum coarsely, irregularly foveate 

 and less coarsely tuberculose, the abdomen coarsely punctured 

 basally, gradually less coarsely posteriorly. Length 13.0 mm. ; 

 width 4.4 mm. Arizona (near Fort Apache), — Warren Knaus. 



geminatus n. sp. 



Enough material has now been accumulated in this genus 

 to demonstrate three clearly marked groups of species ; one, 

 consisting of tristis and allies, another, of the elongate slender 

 forms having the elytra tuberculose to smooth and inhabiting 

 Arizona, New Mexico and adjacent regions north and south, 

 and the third, of those species inhabiting southern California 

 and probably also Lower California, characterized uniformly 

 by a more dilated hind body and smaller prothorax, giving them 

 an obviously different habitus. Five of the third group are now 

 known, including granicollis Horn. The regularly lineate 

 elytral punctures of geminaUis are arranged in an unaccount- 

 ably peculiar manner in groups of two. On closely examining 

 these pairs of approximate punctures, it may be observed that 

 one of them, the anterior in each case, is the setigerous punc- 

 ture attending the tubercles in those forms possessing elytral 

 tubercles, while the other is the ordinary simple puncture of the 

 depressed spaces between the tubercles. As the tubercles are 

 lost in the smoother forms, there is a tendency of these two 

 systems of punctures to segregate and approximate themselves 

 in groups of two, these binary sets forming regular lineate 

 series. This peculiar segregation is best developed in geminatus 

 though observable, to some extent, also on the much rougher 

 and vermiculose, though non-tuberculate, elytra of elongattis, 

 but Dr. Horn has not stated whether or not it occurs in gracilis, 

 — a shining smooth species, with linearly punctured elytra, dif- 

 fering from any other known to me in the absence of an elevated 

 basal thoracic margin. 



