BEMBIDIIN^E 211 



or just inside of, the third stria, the few known species of this group 

 differ radically in the peculiarly short moniliform antennae and in 

 having the apical recurvature of the sutural stria very short. It 

 results from this, that the posterior fovea, not being behind the 

 hooked end of the recurvature, as it is in Tachys and Isotachys, has 

 a position more anterior and more conformable to its usual position 

 in the Bembidiinae. The Icevus group differs from any other of the 

 allies of Tachys in the very minute size of the body, and it includes 

 some of the smallest known Carabids.* The eyes are small or 

 moderate, and the frontal sulci are reduced to small and feeble, 

 widely separate, anterior impressions; the surface is moderately 

 convex and is nearly always distinctly micro-reticulate, though never 

 distinctly dull in lustre. The second antennal joint is very much 

 longer than the third, even more strikingly so than in Tachys 

 proper, and in this respect it differs greatly from Isotachys. The 

 last segment of the outer maxillary lobe is extremely slender. 



After reading carefully the description of the very much larger 

 Tachys trechiformis of Hayward, which the author includes in the 

 Icevus group, I am convinced that it does not belong there, but should 

 form a separate subgeneric group of the genus. Rufotestaceus is 

 also an aberrant species, which, unlike any of the others, is Sonoran 

 in habitat; it is especially peculiar in the sinuate sides of the pro- 

 thorax basally and in having four punctulate discal striae. I ob- 

 tained a single example at its extreme eastern limit of distribution 

 in Texas. 



The species of Microtachys, so far as known to me, may be de- 

 scribed as follows: 



Elytra with but one or two distinct striae 2 



Elytra with four subequal and slightly punctulate striae; hind angles of 



the prothorax sharper, better defined by a short feeble sinus 6 



2 Hind body short, broadly oval, the elytra but little longer than wide. 

 Surface rather notable convex, shining, piceous-black, the prothorax 

 faintly rufous; under surface and legs obscure rufous, the abdomen 

 black; head feebly, the pronotum very obsoletely, micro-reticulate, 



* The remarkable Polyderis minuscula of Motschulsky (Etudes, 1862, p. 36) is said 

 to be only 0.8 by 0.2 mm. in dimensions, which, if correct, would indicate it to be 

 by far the most minute Carabid known. Typical Polyderis is said by Bates to be 

 nothing more than Tachys, but, as Motschulsky included diverse elements in his 

 conception of Polyderis, it is probable that that disposition of it is not strictly final; 

 minuscula, however, is too small for even Microtachys. Scotodipnus also includes 

 very minute species, some of them probably smaller than any known Microtachys. 



