608 COLEOPTERA. 



Byraxis Reitter. Gen. Ins. (Wytsm.), Pselaphidae, p. 206. 



4173. Byraxis halli sp. nov. 



Shining, rufo-piceous, without discernible foveae or punctures, with verv 

 few inconspicuous grey hairs. 



Head rather smaUer than thorax, a little narrowed behind ; eyes not 

 prominent. Thorax of about equal length and breadth, a little wider at 

 the middle than elsewhere. Elytra about twice the size of thorax, sub- 

 oblong, curvedly narrowed to the width of thorax at the base, apices truncate, 

 with sutural striae and a shallow impression inside each shoulder. Hind- 

 body apparently short, considerably deflexed, basal segment rather larger 

 than any of the others. 



Legs moderately elongate, posterior tibiae slightly arched below the 

 middle. 



Antennae not longer than head and thorax, bearing some fine setae ; 

 basal joint oblong, stout, second transverse but not as short as third or 

 fourth ; fifth Y^ry large, strongly transverse, its width double the length, 

 its inner prolongation slightly rounded at the extremity and rather larger 

 than at its junction with the contiguous ones ; joints 6-8 transverse but 

 irregular, seventh rather broader, eighth with a slender basal spine extending 

 outwards ; ninth slightly thicker than eighth at the base but greatly 

 enlarged, and prolonged inwardly, or outwardly, as much as the fifth, 

 slightly curved in front, the thick portion near the middle with a distinct 

 straight spine directed backwards ; tenth rather smaller than ninth, sub- 

 rotundate or subconical, minutely asperate. 



Underside similar to the upper surface in colour and clothing. Anterior 

 trochanters distinctly spined. Metasternum broadly and rather deeply 

 depressed, with a minute upright spine on the centre of its hind margin. 

 Basal ventral segment invisible, second as deeply but not as widely 

 depressed as the metasternum, the cavity with more sharply raised lateral 

 borders, as long as the following three combined ; sixth longer than fifth 

 in the middle, with a transverse depression. 



This belongs to Section XVI, comprising 3052, 3535, and 3536. The 

 antennal structure and sculpture of the lower surface will at once lead to 

 its recognition. Joints 6-10 of the antennae are liable to be twisted, so 

 that it is difficult to decide which is the true upper side ; this causes the 

 prolongation of the ninth joint to be external in one antenna but the 

 reverse in the other. 



3. Length, 1^ mm. ; breadth, nearly f mm. 



Fen7. — Rather more slender, hind tibiae similar. Basal joint of antennae 

 oblona; but no thicker than the shorter second, third obconical, longer than 

 the short fourth ; fifth rather larger ; sixth and seventh beadlike and 

 transv(>rse, eighth slightly broader and shorter, ninth distinctly broader, 

 about half the size of the transverse tenth, the eleventh conical, largest, 

 as long as preceding three together and more evidently pubescent. Under- 

 side simple. 



Mount St. Arnaud, Nelson. Two males and four females; 15th June, 

 1916. Named in honour of Mr. T. Hall, the indefatigable naturalist who 

 has brought to light a great many interesting forms of Psela.pjiidae, some 

 of wliich still remain unnamed. 



