so 



FAMILY II. CAB ABIDES. 



XIX. Taciiys Schaum. 1860. (Or., "swift,") 



Very small black or brownish species having the characters of 

 the tribe BemUdiini. Front tibiae 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 the bark of partly decayed logs and 

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

 flats. "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 : 

 Hay ward.— - 1 A Study of the Species of Tachys of Boreal Amer- 

 ica" in Trans. Amer. Ent. Soc, XXVI, 1899. 191-238. 

 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- 

 meniform punctures which are entirely absent in the other group. 

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

 as recognized, their presence or absence can be readily determined, 

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

 treated by Hayward 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. a, mentum of T. tivax; b, mentum of T. proximus; c, thorax of T. intvnus; d, thorax of T. (rim 



(After Hayward.) 



KEY TO GROUPS OF INDIANA TACHYS. 



a. Mentum ^y^thout large punctures behind the median tooth (Fig. 52. a) ; 

 marginal stria of elytra interrupted or less deep at middle. 



Group A. 



aa. Mentum with two large forameniform punctures behind the tooth. 

 (Fig. 52, M Groll P B - 



