370 CASEY 



sparsely and confusedh- punctulate; abdomen rather coarsely and 

 closely punctured throughout, the metasternum extremely coarsely. 

 Length 5.0 mm. ; width 2.3 mm. Arizona pulverea Horn 



Form oblong, piceous-black, moderately shining, the antennze pale, 

 the legs brownish ; head densely and somewhat strigosely punc- 

 tate, the epistomal lobe obtusely triangular ; prothorax at the 

 middle about twice as wide as long, the sides regularly arcuate, 

 the base and apex nearly equal, with the angles obtuse ; disk 

 moderately coarsely and closely punctate, somewhat strigose at 

 the sides ; ehtra at base slightly wider than the prothorax, with 

 striae of fine punctures not closely placed, the intervals irregularly, 

 biseriately punctate, the punctures of the striae and intervals con- 

 fused behind the scutellum; sterna very coarsely punctured, the 

 propleurae strigose ; abdomen moderately coarsely, not closely 

 punctured. Length 4,0-4.5 mm. Lower California (Sierra 

 Laguna) obtusa Horn 



Although Dr. Horn has not described the mandibles or the 

 form of the prothoracic base in obtusa, which is unknown to me, 

 I believe, from the general nature of its characters, that it is to 

 be associated with fiilverea in the subgenus Pimalius. The 

 very radical difference in the mandibles seems to indicate that 

 Pimalius really ought to have generic rank, but because of its 

 general resemblance to the normal Trimytis, I leave it with the 

 indicated status for the present. Of the two Mexican species 

 described by Mr. Champion in the " Biologia," obovata, from 

 Chihuahua, is evidently an associate of fruinosa and a normal 

 member of Trimytis, huXjlohri, from the vicinity of the City of 

 Mexico, because of its prominent and scarcely emarginate eyes, 

 must inevitably form another genus, for which I would propose 

 the name Tlascalinus (n. gen.) ; it may take its place immedi- 

 ately after Trimytis in the above table. 



Prometopion n. gen. 



This genus in its general form and habitus, constitutes a 

 satisfactory transition from Trimytis to Chilometop07i . The 

 hind wings appear to be rather well developed, but, from the 

 heavier form of the body, the flight is probably more laborious 

 than in the lighter and more slender C/iilomctopoii. The man- 

 dibles are thick and heavy, with a broad smooth external ridge 

 above, clasping the epistoma as in Trimytis, but the apex is 

 broad and very obtuse, feebl}' bifid, the upper lobe very wide 



