98 CLA.VICORXIA. [Trichonyx 



TRICHONYX, Chaudoir. 



This genus in its widest sense comprises about eight or nine European 

 species, of which two are British. Reitter, however, has formed a new 

 genus, Amauronyx, to receive T. Maerlcelii and three other European 

 species, which differ from Trichonyx proper in the relative length of the 

 abdominal segments ; both our indigenous species are very rare ; they are 

 distinguished from the other members of the tribe Euplectina by the fact 

 that the tarsi have two very unequal claws ; the continental genus Fa- 

 ronus, which is not represented in Britain, has the tarsi furnished with 

 two equal claws, while in Eupledus and its allies the claws are single. 

 The species of Trichonyx are found, as a rule, in company with 

 ants. 



I. First visible dorsal segment of abdomen elongate, much 



longer than the second ; form narrower and more 



linear ; elytra obsoletely and not closely punctured . . T. MAERKKLII, Aube. 



II. First visible dorsal segment not elongate, only slightly 

 longer than second ; form broader and less linear ; 



elytra very closely and finely punctured T. SULCICOLLIS, Reich. 



T. Maerkelii, Aube (Amauronyx Maerkelii, Reitter). Elongate, 

 slightly convex, entirely rufo-testaceous or ferruginous, sparingly pubes- 

 cent ; head as broad as thorax, subtriangular, with deep frontal furrows, 

 eyes not large or prominent ; antennas rather long and robust, penulti- 

 mate joints transverse, last joint large, ovate, subacuminate at apex ; 

 thorax longer than broad, dilated in front, broadest before middle, and 

 narrowed to base, impunctate, with a central channel, and three f ovese at 

 base connected by an impressed line ; elytra almost double as long as 

 thorax, obsoletely punctured, with a deep dorsal stria extending beyond 

 middle of disc ; abdomen with the first visible dorsal segment elongate ; 

 legs rather long, reddish testaceous. L. 2 mm. 



Male with the trochanters of the intermediate legs furnished with a 

 small blunt tooth. 



In moss, dead leaves, under stones, &c. ; usually in company with ants ; rare ; 

 Mickleham (Cbampion) ; Esher (Power) ; Seaford, Devon, August, 1865 (Water- 

 house), in company with S. glabratus and a small yellow Myrmica ; Guestling near 

 Hastings ; Eastbourne (Waterhouse) ; Sandown, Isle of Wight, April, 1884, where I 

 captured three specimens, in company with ants, under stones (one specimen of B. 

 glabratus occurred at the same time) ; Freshwater (Gorham) ; Scarborough (Lawson); 

 the late Mr. Garneys captured one specimen by sifting dead leaves in winter, I 

 believe in Suffolk. 



T. sulcicollis, Reich. The largest and finest of our indigenous 

 Pselaphidte ; entirely rufescent, moderately shiny, with thick and 

 short yellowish pubescence ; head narrower than thorax, eyes not large, 

 moderately prominent, antennae rather long, all the joints with the 

 exception of the penultimate longer than broad ; thorax transverse, 



