LECONTE— SYNOPSIS OF PTEROSTICHUS. -235 



under the particular groups in which they occur. The following table will express 

 the relation of the groups among themselves. 



A. Margine eljtrorum bistriato. 



B. Margine eljtrorum unistriato. 



1. Thorax tenuiter marginatus ; parapleurse breves. 



a. Elytra punctis dorsalibus nullis. Sp. 1 — 17. 



b. Elytra bipunctata. Sp. 1 8. 



c. Elytra tripunctata, stria scutellari distincta. Sp. 19. 



d. Elytra tripunetata, stria scutellari nulla. Sp. 20 — 21. 



2. Thorax tenuiter marginatus ; parapleurse longse. 



e. Thorax basi unistriatus ; elytra tripunetata. Sp. 22 — 28. 



f. Thorax basi bistriatus ; elytra tripunetata. Sp. 29 — 32. 



g. Thorax basi unistriatus; elytra 5-punctata. Sp. 33 — 34. 



3. Thorax fortius marginatus. 



h. Thorax basi bistriatus ; elytra bipunctata. Sp. 35 — 38. 



i. Thorax basi foveatus ; elytra bipunctata. Sp. 39. 



k. Thorax basi foveatus ; elytra 4-punctata. Sp. 40. 



1. Thorax basi foveatus ; elytra irregulariter striata. Sp. 41. 



m. Thorax basi bistriatus ; elytra tripunetata. Sp. 42 — 44. 



A. 



None of the species of this genus are found in North America ; they may be 

 divided into several groups, such as A.bax, Molops, &c., according to the form of the 

 thorax. Feronia quadricollis LeConte, An. Lye. 4, 343, does indeed belong here, but 

 it is no American insect, and is identical with Pterostichus parallelus of Europe. 



a. 



We have here a large number of species, usually of a slender form, with the thorax 

 quadrate and gradually narrowed behind ; the margin of the elytra ^is moderate and 

 has but a single stria; the elytra have no dorsal punctures; the parapleurse are 

 short. For the better determination of the species, which are frequently very closely 

 allied, this group may be subdivided : 



o. Thorace basi immarginato. Sp. 1 — 9. 



;3. Thorace margine basali medio interrupto. Sp. 10 — 15. 



y. Thorace basi tota marginata. Sp. 16 — 17. 



The thorax is trapezoidal, "narrowed behind, the posterior angles distinct, not promi- 

 nent ; the basal impression is linear and single except in the two first species in which 

 there is a short outer impression, margined in the first by a very faint carina ; the 

 base is entirely without a marginal line. The anterior tarsi of the males are variable 



