Cnupeta.] sxaphtlinid^. 143 



Male with the head impressed and the ventral plate of seventh 

 segment of hind body narrow, and distinctlj^ produced. 



On muddy banks of I'ivers and streams j common throughout the kingdom. 



€r. coerulea, Sahib, (rijncola, Kies., carhonaria, Sharp, I.e.). Very 

 like the preceding, but rather larger, and not so shining, and of a dis- 

 tinct blue colour with the legs and antennae entirely blue black except 

 that the tarsi and sometimes the knees are more or less testaceous ; the 

 head is impressed in both sexes ; in colour it much resembles Tacliyusa 

 flavifarsis and Dianous. L. 3 mm. 



On banks of streams ; very rare ; banks of Derwent, near Derby (J. T. Harris) ; 

 Charlton, nenr Manchester, and banks of Ballin, Cheshire (J. Chappell) ; Scarborough 

 (Lawson); Nortliumberland district, the Wansbeck (Power); Scotland, banks of 

 Nith (Sharp), Crook of Devon (Power). 



TACKVUSA, Erichson. 



As at present constituted this genus contains twenty-eight species, 

 tAventy from the European region, four from North America, two from 

 Chili, and two from Central America ; the species occur chiefly on the 

 sandy banks of rivers and streams, and are exceedingly swift runners ; the 

 two sea-side species, T. %ivida and T. sulcata, are now separated off under 

 the genus Myrmecoi^ora, Saulcy {Xenusa, Rey). 



Our British species may be divided as follows, but some of them are 

 rather hard to distinguish by a table : — 



I. Hind body very strongly narrowed at base. 



i. Elytra longer ; legs testaceous T. consteicta, Er. 



ii. Elytra shorter; legs pitchy red or brownish with 



tarsi lighter T. coaectata, Er. 



II. Hind body distinctly but not strongly narrowed at 



base T. scitula, Er. 



III. Hind body parallel-sided or narrowed towards apex. 



i. Upper surface with a strong bluish reflection . . . T. flavitahsis, Sahib. 

 ii. Upper surface black. 



1. Upper surface shining ; legs lighter T. uiibeatica, Er. 



2. Upper surface dull ; legs darker. 



A. Eyes not prominent ; head and tliorax sub- 

 quadrate; antennaj longer T. atea, Grav. 



B. Eyes prominent ; head and thorax strongly 



transverse; antennae shorter T. concoloe, E;*. 



T. constricta, Er. Elongate, narrow, pitchy-black, shining, clothed 

 with fine and rather long pubescence ; head large, about as broad as 

 thorax, narrowed behind, antennae moderately long, more or less dark, 

 with the basal joints testaceous, second and third joints about equal in 

 length, penultimate joints slightly transverse ; thorax longer than broad, 

 almost oval, very finely and thickly punctured, plainly narrower than 

 elytra ; elytra distinctly longer than thorax, with shoulders rounded, very 

 finely, thickly, and somewhat rugosely punctured ; hind body strongly 

 narrowed at base, where it is about half the breadth of the elytra, and 



