56 BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



Diagnostic characters. — In collections the females of the present 

 species are usually associated with subnitens^ while the males are 

 placed with qnadricoUh or carhonaria. 



On account of its large size and dull integuments ampla has to be 

 carefully differentiated from si/hnitens, from which it differs in the 

 sides of the pronotum, being more strongly rounded and widest at or 

 in advance of the middle, by the less prominent apical angles, and the 

 subgeneric characters. 



AmpJa bears no resemblance to a typical carhonaria; the dull luster, 

 fine and unimpressed elytral punctuation readily sejDarates it from 

 the latter species, and besides the males are quite fusiform in outline 

 and the legs are distinctly longer, characters never observed in car- 

 honaria. A male from Santa Fe canyon, New Mexico, has the strial 

 punctures of the elytra moderately large and slightly impressed, but 

 the form is elongate and fusiform. 



From quadricolUs it differs by the anterior spurs of the anterior 

 tibise of the females, being much narrower and evidently narrowed 

 from base to apex, and by the long legs. 



Specimens from about Brownsville, Texas, are more shining than 

 those observed from elsewhere. 



For characters separating it from its race dolosa.^ see below. 



In fact, am])la is the largest species^ in the present section of the 

 subgenus. 



The mentum is very moderate for so large a species and varies quite 

 a little in form — triangulo-trapezoidal to trapezoido-parabolic ; the 

 surface is moderately strongly punctate, and the seta^ are very small, 

 laterally with shallow foveate impressions, rather broadly and longi- 

 tudinally convex at the middle. 



The prosternum is variable, usually feebly convex between the coxa\ 

 rounded behind and Aery feebly mucronateat middle, or witli a mod- 

 erate mucro; souietimes lioi'izontally |)rodiic('(l. comjiressed. and ob- 

 licjuely ti'uncate. 



Mesostei'num more oi' less declivous and feebly concave. 



The metasternal i)ro('ess is about as wide as the abdoniinal salient 

 is long. 



The abdominal intercoxal process is slightly transverse (male) or 

 sulujuadrate (female), and about a fifth of its Avidth Avider than the 

 metasternal ])rocess, and sube<iiial in length to that of the post-coxal 

 I^art of the same segment, the latter being <|uite e(|iial to the second 

 (male), the second segment a little longei- (female) than the former. 

 The third segment is about a third longer than the fourth. 



The profemora are feebly tumid to rather strongly so (male), less 

 strongly and as variable in the female, in both sexes usually more or 

 less slightly compressed, or subcylindrical, in transverse section in 

 certain specimens (males) ; tibial grooves not strongly limited by the 



