SO 



F \MILY IT. - CAIJAP.ID.K 



XIX. TACIIYS S.-haiiui. 1SliO. (Gr., "swift") 



Very small black or brownish species having the characters ol' 

 the tribe Bembidiini. Front tibia* obliquely truncate at apex; 

 elytra glabrous, either striate or wholly without stria, except 

 that at suture, which is recurved at apex. They occur for the most 

 part in damp places, beneath Hie bark of partly decayed logs and 

 stumps; also in moss and ant hills and beneath chunks on mud 

 Hats. When uncovered they run very rapidly, whence the generic 

 name. About 45 species are known from the United States; of 

 these 15 have been taken in Indiana. 



The only paper treating of the genus is by: 



Hai/irard. "A Study of the Species of Tachys of Boreal Amer- 

 ica" in Trans. Amer. Ent. Soc., XXVI, 1S!M). 11)1-238. 



For convenience Hayward divided the genus into nine groups. 

 his primary division being based upon the presence or absence of 

 punctures on the mentum. Of this character he says: "The 

 mentum varies in the different species being more or less emargi- 

 nate in front, with a tooth of varying prominence at the bottom of 

 the emargination. In rather more than half of the United States 

 species there may be observed, behind the tooth, two large fora- 

 raeniform punctures which are entirely absent in the other group. 

 These are not difficult to detect, even with a hand lens, and as soon 

 as recogni/ed. their presence or absence can be readily determined, 

 even in the smallest forms." Since only one-third of the species 

 treated by Ilayward occur in Indiana, they will be separated into 

 but two groups, and this is done only to lessen the length of the 

 keys to species. 



Fig. 52. n, mentum of T. rirar: b, mentum of T. proximvs; c, thorax (if 7'. iiimnitt; il, thorax of T. iri].uncta ! .us. 



(After Hayward.) 



KKY TO (iROll'S OF INDIANA TACHYS. 



ii. Mentum without hir^e punctures behind the ini'di;in tooth (Fij;. 51.', ") ; 

 marginal stria of elytra interrupted or less deep at middle. 



Group .1. 



ii'i. Mentnm with !\vi> lar.uc I'orainenirorii! punctures behind the tooth. 

 <Fig. f)L'. !>.} Group /?. 



