46 GEO. H. HORN, M. D. 



closely resemble each other in form and color, and may be known by 

 the clypeus being more impressed in the latter species and with the 

 elevated angulate line behind its margin. In well marked specimens 

 of either the presence of the slender teeth on either side of the mid- 

 dle truncation of dentiger, or the broadly emarginate and acutely 

 angulate clypeus of colorade)isis will easily separate them. 

 Occurs in Colorado. 



A. bicolor Say. — Oblong, slightly wider posteriorly, sulxlepressed, piceous 

 shining, elytra often with round reddish yellow spots on the alternate intervals 

 often more or less confluent at base, metasternum, abdomen and legs pale yellow. 

 Antennae testaceous, the club darker. Head rather densely, moderately coarsely 

 punctured, front without tubercles ; clypeus broadly emarginate, the angles well 

 marked, sides feebly arcuate, the geuse very little i)romiuent, obtuse. Thorax 

 nearly twice as wide as long, slightly narrower in front, sides feebly arcuate, 

 hind angles broadly rounded, base arcuate with distinct marginal line, disc con- 

 vex, moderately closely punctate, the punctures somewhat unequal, denser and 

 coarser near the sides. Elytra as wide at base as the thorax, humeri distinct, 

 disc rather deeply striate, strise crenately punctured, intervals convex, sparsely 

 irregularly punctate. Body beneath sparsely indistinctly punctate. Anterior 

 tibise smooth in front, tridentate externally and crenulate above, the tirst tarsal 

 joint very short, the second as long as the next two together. Posterior femora 

 sparsely finely punctate, the first tarsal joint as long as the next three. Length 

 .18-.24 inch ; 4.^-6 mm. 



Hale. — Anterior tibial spur inserted opposite the upper tibial tooth. Thorax 

 less densely punctured. Middle and posterior femora fimbriate posteriorly, the 

 posterior tibiae sparsely fimbriate on the inner side. 



Female. — Anterior tibial spur inserted opposite the middle tooth. Thorax 

 more obviously narrowed in front and more densely punctured. Legs not fim- 

 briate. 



The vast majority of sjDecimens of this species are entirely black 

 above, but individuals are not rare in which the alternate intervals 

 beginning with the third have small round reddish yellow spots, 

 sometimes the base and scutellar region are pale. 



The length of the second joint of the anterior tarsus seems rather 

 an unusual character, and it has not been observed in any other 

 species that the anterior tibial spur of the male is inserted so far dis- 

 tant from the apex. 



Occurs from Can. to Tex., rarely in Massachusetts (Blanchard). 



A. lu.vatus n. sp. — Oblong, slightly broader posteriorly, piceous nearly 

 black, elytra dull red. legs brownish, surface feebly shining. Antennae testa- 

 ceous, club darker. Head moderately convex, without frontal tubercles, surface 

 finely alutaceous, rather closely coarsely punctured posteriorly, more coarsely 

 jjunctate at sides, at middle more finely punctate ; clypeus broadly emarginate, 



