90 



FA M I LY II.- — CATtABIDyE. 



XXIV. Pterostichus Boil 1813. (Gr.. "wing -f compact.") 



Black or greenish-shining beetles of medium or large size, hav- 

 ing the characters of the tribe as above given. Form elongate, more 

 or less depressed ; head but little constricted behind the eyes • mar- 

 gin of elytra strongly interrupted posteriorly. 



The members of this genus are among the most common of our 

 Carabida?. They are found in woods and along the borders of fields 

 under logs, stones and leaves. A number of the species hibernate 

 in the perfect stage. Dr. Forbes dissected thirteen specimens of 

 this genus and found that 43 per cent, of the food was of insects, 

 canker worms, caterpillars, etc. The vegetable food was of fungi 

 and flowering plants. 



The principal papers dealing with the genus are as follows : 



LeConte. — "Synopsis of the Species of Pterostichus and Allied 

 Genera Inhabiting Temperate North America." in Journ. 

 Phil. Acad. Nat. Sei., II. 1852. 225. 



LeConte.— 'The Pterostichi of the United States," in Proc. 

 Phil. Acad. Nat, Sci., 1873, 302. 



LeConie.—' ' Synoptical Table," in Bull. Brook. Ent. Soc. Y. 

 1882. 15, et seq. 



WicMam.— In Journ. N. Y. Ent. Soc,, III. 1895, 181. 



About 125 species are known from the United States. Of these 

 24 have been taken in Indiana, while 5 others may occur. For con- 

 venience the Indiana species are first arranged in four groups, and 

 these are then treated in order. 



KEY TO GROUPS OF INDIANA PTEROSTICHUS. 



a. Dorsal punctures none or one only. Group A. 



aa. Dorsal punctures two or more. 



J). Last joint of palpi cylindrical, truncate at tip; size larger, usually 

 10 or more mm. 



c. Side pieces of metathorax short, their length distinctly less than 

 twice their width at base. Group B. 



cc. Side pieces of metathorax long, narrowed from base to apex, their 

 length being more than twice the width at base. Group C. 



hl>. Last joint of palpi elongate-oval, scarcely truncate; size smaller, not 

 over S.5 mm. Group D. 



Group A. 



To this group belong smali or medium sized species either wholly 

 without dorsal punctures or with one puncture behind the middle 

 on the third interval, close to the second stria, They have the thorax 

 usually rounded or trapezoidal, much narrowed behind, the margin 

 narrow, not reflexed, the base without a marginal line. Six species 



