380 CLAVicoENiA. [Alacronychus. 



subsequently been taken in numbers by Mr. Hf^rris. Mr. E. Brown^ and 

 Mr. W. Garneys, and sparingly by Mr. Blatch and myself; no otber 

 British locality is known, but there must be many others, as an aquatic 

 insect is not likely to occur in a single stream in the centre of Engknd 

 and in no other. 



The larva of M. qiiadrituherculaius is described and figured by Perris, Ann. Fr. 

 1863, p. 621, t. 14, fig. 1 — 15 ; it is of an obscure dii-ty-f?rev colour above with a badly 

 limited lighter band on each side of the central line, under-side pale; upper surface 

 rough ; firm elongate, a little broader in front than behind, gradually narrowed to 

 apex; head small, much narrower th:in thorax; antennas short; prothorax very large, 

 nearly as loner as the next three segments together, meso- and nietathorax and the 

 first eight abdominal segments of about equal length, ninth abdominal segment elon- 

 gate, narrowed to apex, which is emarginate and furnished with long setse ; legs 

 moderately long, termiuating in a single stout cluvv. 



m. Quadrituljerculatus, Miill. Elongate, narrow, black, some- 

 times very faintly metallic, front margin of thorax reddish ; under-side 

 and legs pitchy ; head rather long ; forehead very thickly and rngosely 

 punctured; thorax somewhat narrower than elytra, longer than broad, 

 narrower in front, finely mai'gined at sides, very finely punctured, with 

 two distinct tubercles at base ; elytra with distinctly punctured striae 

 which become gradually weaker towards apex, second interstice on each 

 side near base raised into a strong longitudinal tubercle which is furnished 

 with a distinct crest of thick upright setjB ; the interstices are more or 

 less setose ; legs very long, tarsi curved and furnished with strong claws. 

 L. 2i--3 mm. 



On submerged logs and stumps ; has only occurred in one locality in Britain, viz. 

 the River Dove near its confluence with the Trent between Willington near Repton 

 and Burtou-on-Trent. 



PARNINA. 



Under this tribe Dr. Horn includes the Larina, in which case the 

 character of the short antennae above given will not hold good except for 

 our native species, as the antennae in Lara are long and slender ; the 

 latter genus, however, must, apparently, be separated from Panius and 

 its allies ; the two British species Parniis and Potaininus are rather long, 

 oblong, subcylindrical insects, with long slender legs, and with the antennae 

 scarcely apparent when the insect is viewed from above ; the upper 

 surface is thickly clothed with yellowish or greyish or sometimes fuscous 

 pubescence ; they may be distinguished as follows : — 



I. Intermediate coxae separate ; thorax without impressed 



lines at sides POTAMINTTS, Sliirm. 



J I. Intermediate coxae contiguous; thorax with impressed 



lines at sides ParStts, F. 



POTAIMtXNUS, Sturm {Dryoj)S, I>each, nee Olivier). 

 This genus contains one species from Europe, one from Java, and 



