ROLAND HAY WARD. 195 



large punctures near the middle of the posterior transverse impres- 

 sion. This is represented on Plate VI, figs. 10 and 11. 



Many characters of great importance are derived from the elytra. 

 These are rounded at tip in all the groups, except that containing 

 cenescens, in which the apex is subtruncate. The dorsal punctures 

 are usually two in number and differ in position in the different 

 groups. In wnescens, however, I have been able to detect but a 

 single puncture, which is so small that it can be located only by the 

 seta arising from it. The recurved portion of the sutural stria, to 

 which allusion has already been made, also affords several useful 

 characters. These differences are well represented in the figures 

 (PI. VI, figs. 1-8). The other dorsal stride vary considerably, espe- 

 cially in number, but I am inclined to think that too much value 

 has been assigned to this latter character by several authors. In 

 most species they are impunctured, rarely distinctly punctate. The 

 marginal stria is usually broadly interrupted at middle, rarely 

 (ephippiatus, etc.) deep and entire, sometimes with the basal portion 

 obsolete and represented by punctures, or even (Icevus) completely 

 effaced. In the latter case the marginal setigerous punctures, which 

 are present in all our species near the humerus and apex, assume 

 unusual prominence. 



In nearly all our species the first two joints of the anterior tarsi 

 are dilated in the males (PI. VI, fig. 15), although less broadly than 

 in Bembidium. In corruscus (PI. VI, fig. 16) and several other 

 species of the ninth group only the basal joint is dilated, while in 

 ephippiatus and its allies and cenescens the tarsi are similar in the 

 sexes. The males are usually rarer than the females. 



All the species of Tachys are of small size, the largest (sellatus) 

 being about .16 inch (4 mm.) long, while the smallest (Jcbvus) meas- 

 ures only .05 inch (1.25 mm.) in length. Most of them are found 

 in moist places, or are riparial in their habits. Some occur under 

 bark, while a few are myrmecophilous. They are entirely unknown 

 to me in their early stages, and, so far as I am aware, the larva and 

 pupa of but a single species (nanus) have been described.* 



The genus is represented on both sides of the continent, but the 

 species are more numerous in the southern than in the northern 

 portions of the country. 



A few words are necessary with regard to the plate which accom- 



* Perris, Hist, pin Mar. (1862), 1863, i, pp. 439-461, figs. 510-516. 



TRANS. AM. KNT. SOC. XXVI. JANUARY, 1900. 



