126 ADEPHAGA, [Trechus. 



A. Elytra with strise broad and deep 



to margins T. IAPIDOSUS, Daws. 



B. Elytra with striaj plainly feebler 



at sides. 



a. Size larger ; thorax cordiform ; 



posterior angles sharp . . . . T. etibens, F. 



b. Size smaller; thorax not cordi- 

 form ; posterior angles blunt . T. minutus, F., and v. OBTUSUS, Fr. 



C. Elytra with three deep striaj near 

 suture, the second and third, as a 

 rule, not or scarcely reaching be- 

 yond middle T. eivttlaeis, Gi/ll. 



ii. Posterior angles of thorax completely 



rounded T. SECALIS, Payk. 



T. discus, F. Testaceous red, rather pubescent, elytra with a com- 

 mon l)lackish or blue-black patch behind middle ; eyes black, prominent ; 

 antennae long, testaceous ; thorax cordate, much narrowed behind, pos- 

 terior angles acute, projecting, disc convex, dorsal furrow deep, base 

 with a deep fovea on each side ; elytra long, with sides slightly rounded, 

 finely striated, interstices finely but distinctly punctured, third stria with 

 two large pores which stretch over the fourth interstice ; legs j^ale 

 testaceous. L. 4|-5 mm. 



Very local, but not uncommon in the midland counties : it occurs on the banks of 

 streams and rivers; banks of Trent, Repton and Newark ; hanks of Dove, Burton-ou- 

 Trent ; banks of Derwent below Derby ; banks of Severn, Bewdley and Tewkesbury ; 

 Draycott ; Salford Priors; Boxted, Essex; banks of Ribble, Sawley, Lancashire; 

 Hornsea, Pontefract, Scarborough, Yorkshire ; Vale of Towey, Wales ; it has also 

 occurred in Norfolk, Suffolk, Cambridgeshire, and Bedfordshire ; also formerly at 

 Netting Hill ; it is not recorded from the extreme north or south of England, or from 

 Scotland or Ireland. 



T. micros, Herbst. More elongate, and narrower than the pre- 

 ceding, with the elytra more parallel-sided : it is also of a duller testa- 

 ceous colour, and has the dark markings on the elytra obscure and often 

 absent or nearly so ; eyes not prominent ; antennae testaceous ; thorax 

 much as in T. discus, except that it is rather narrower in front, with the 

 sides somewhat less strongly narrowed behind, and the posterior angles 

 quite as sharp, but slightly less prominent ; elytra finely striated, inter- 

 stices very thickly and finely punctured, with two pores on each as in 

 the preceding species. L. 4 mm. 



Very local, but much more widely distributed than the preceding : it is found in 

 the majority of the localities just mentioned for discus, and further occurs at Darenth 

 Wood, Horsham, Tonbridge, Matlock, York, Carlisle, .and other places; Northumber- 

 land and Durham in rejectamenta on the banks of streams ; Scotland, rare, Tweed, 

 Forth, Solway, Clyde, Argyle ; it does not, however, appear to be a southern insect : 

 these two species conceal themselves in the crevices of sandy or clayey banks ; I have 

 taken both by dashing water against the sides, and thus causing them to run out 

 from their hiding-places. 



T. long-icornis, Sturm. {Thalassophilus, Woll.). Somewhat re- 

 sembles a small specimen of the preceding, but may at once be distin- 

 gui.shed by its very long anteuuie, which arc at least two-thirds as long 



