AMERICAN COLEOPTERA. 151 



The differences between the sexes are not apparent. 



The species of this genus are closely allied and differ by compara- 

 tively slight characters. Color must be considered of very doubtful 

 value, and too great importance should not be attached to slight 

 variations in punctuation. 



In presenting a synoptic table of our species, I find myself com- 

 pelled to make use of characters entirely different from those hereto- 

 fore proposed. 



Base of mandibles distant from the eyes pratensis. 



Base of mandibles very close to the eyes. 



Head behind the eyes with numerous punctures and short hairs. 



Thorax rufous flavicollis. 



Thorax black. 



Scutellum usually sparsely punctured pronns. 



Scutellum densely punctured deilSUS. 



Head behind the eyes smooth or nearly so. 

 Antennae subclavate, the outer five joints transverse flavipes. 



A. pratensis Lee. New Species, 1863, p. 34. — Black, shining. Elytra 

 conjointly a little wider than long, surface rather coarsely but not densely 

 punctured, punctures at the sides finer and denser, sparsely clothed with 

 brownish hair. Scutellum sparsely punctate. Abdomen sparsely punctate and 

 clothed with brownish hair. Length .28 inch; 7 mm. 



Not only are the mandibles distant at base from the eyes but the 

 insertion of the antennae also. The palpi are rather longer and more 

 slender than usual. 



One specimen, Kansas. 



A. flavicollis Sachse. Stettin Zeitschr. 1852, p. 143. — Head black, shi- 

 ning, anterior puncture at the margin of the eye, the second distant and nearly 

 frontal, the two posterior on the occiput, placed obliquely. Antennse piceous, 

 testaceous at base. Thorax rufous, shining, normally punctured. Scutellum 

 sparsely punctate. Elytra black, shining, sparsely pubescent, conjointly a 

 little wider than long, surface coarsely and moderately closely, sub-muricately 

 punctate, punctures a little finer and denser along the base and sides. Abdo- 

 men sparsely punctate, segments smoother posteriorly. Legs rufo-testaceous. 

 Length .20— .22 inch; 5—5.5 mm. 



Occurs from Pennsylvania to Kansas and Texas. 



I am unable to find any real differences between this species and 

 the next except in color. If the two are united it will merely parallel 

 what occurs in many Quedius and in Diochus Schaumii. 



A. proniis Erichs. Staphyl. p. 521; gilensis Lee. New Species, 1863, p. 

 34. — Black, shining. Antennse piceous, usually paler at base. Legs variable, 

 usually testaceous often piceous. Length .18 — .24 inch; 4.5 — 6 mm. 



The other characters are already given in the preceding species. 



Occurs all over the United States on both coasts. 



