Arrognathus.] staphylinid,!!! 39 



tliis genus ; it is scarce on the Continent, and is one of our rarest British 

 insects ; it occurs under dead decaying leaves on the edges of stagnant 

 pools, almost, if not quite, in the water. 



A. mandibularis, Gyll. Elongate, linear, somewhat depressed, of 

 a dull ferruginous-red colour, with the head black, or pitchy brown, and 

 the thorax often dark pitchy red ; the elytra are lighter red, with the 

 apex sometimes a little infuscate ; head subtriangular, rathcu' strongly 

 and sparingly punctured ; antennae entirely red, rather long, with the 

 last three joints larger than the rest ; thorax subquadrate, or slightly 

 longer than broad, considerably narrower than elytra, very slightly and 

 gradually narrowed behind, with posterior angles almost right angles, 

 rather finely and sparingly punctured, Avitli a smooth central line, which 

 is abbreviated in front ; elytra considerably longer than thorax, very 

 finely shagreened, and besides finely and rather thickly punctured in 

 irregular rows, with three more or less obsolete raised lines on each ; 

 hind body parallel-sided, more shining than elytra, very finely sha- 

 greened, smooth and rather shining at apex ; legs testaceous-red. L. 

 5|-6 mm. 



Male with the first ventral segment furnished behind with a tubercle 

 in centre, seventh slightly and obtusely prolonged in middle. 



In rotting leaves, on the banks of stagnant ponds, especially in woods ; once taken 

 on tbe wing ; very rare ; Darenth Wood j Claygate, Surrey ; Epping Forest ; Ton- 

 bridge. 



COMPSOCHZZiUS, Kraatz. {Planeiisfomus, Duval.) 



The species belonging to this genus bear a rather close relation to 

 Acror/na/Ju's, but are widely separated from them by the structure of the 

 tarsi, which are five-jointed in the latter genus, whereas in Compsochilus 

 they are all three-jointed ; the elytra, moreover, have no border, whereas 

 in Arrognathus they are finely bordered at the sides ; the genus com- 

 I^rises about a dozen species, which are all found in Europe with the 

 exception of two from Algeria and Morocco : they are slow in their 

 movements and live in woods and damp places ; they are said to fly just 

 before twiliirht. 



C. palpalis, Er. Elongate, narrow and linear, testaceous, rather 

 shining, Avith the head, metasternum, and usually a space before apex of 

 hind body, darker; head subtriangular, very finely shagreened, and 

 rather strongly and sparingly punctured, clypens smooth and shinino-, 

 forehead with a slight inqjression on each side ; antennae testaceous 

 with the five last joints darker ; these joints are also larger than the 

 rest, the three last being the largest ; thorax a little longer than broad, 

 much narrower than elytra, gradually and slightly narrowed behind, with 

 posterior angles somewhat obtuse, obsoletely shagreened, finely and 

 diffusely punctured at sides, and Avith two scries of punctures on disc, 

 separated by a rather narrow, impunctate, somewhat raised interval ; 



