Limnius.'] CLAVICORNIA. 379 



shorter than broad, gradually narrowed in front, with the disc very finely 

 punctured, and impressed at si !es with strong engraved lateral lines which 

 are curved near base and slightly converge in front ; elytra almost three 

 times as long as thorax, a little dilated behind middle and depressed on 

 disc before middle, and raised before base into two broad and blunt more 

 or less distinct prominences, which are otten not very apparent, striie 

 strongly punctured, interstices rather flat and finely punctured in rows ; 

 at the sides are two carinate lines, the first of which continues the line 

 on thorax ; legs fuscous-reddish, tarsi lighter. L. lj-l| mm. 



In running water, found under the same conditions as Elmis ; somewhat local, but 

 rather common and widely distributed throughout the kingdom. 



Zi. rivularis, Rosenh. Smaller than the preceding, and more parallel- 

 sided, with the disc of the elytra much more even ; the disc of the thorax 

 is more closely punctured and duller, and the lateral engraved lines are 

 more parallel, although the usual distinction that they are straight and 

 parallel to the sides does not hold good always, as in some of Dr. Power's 

 specimens they are distinctly nexuose at base ; the striae of the elytra also 

 are finer, although the punctures are quite as strongly marked ; in most 

 of the specimens I have seen the thorax is longer and less transverse than 

 in L. tuberculvttis ; the legs are fuscous-red or pitchy-red with the tarsi 

 lighter. L. 1 mm. 



In running water ; local ; Woking (taken in abundance by Dr. Power) ; Northum- 

 berland district, Rothley Lakes (Power) ; it hns also been taken recently by Mr. T. 

 Wood at Birchingtou, near Margate. Dr. Sharp has remarked that, although not un- . 

 common in Southern Europe, it has not previously been found further north than 

 Central France. 



Xi. troglodytes, Gyll. Broader than the preceding, but otherwise 

 much resembling it in general shape ; it is a little narrower and more 

 parallel-sided than L. tuliercula/us ; the sides of the thorax are more 

 parallel and less rounded in front than in either of our other two species, 

 and the elytra have the striae evidently less strongly punctured, and the 

 central interstices more closely and finely punctured ; the raised lines on 

 the thorax are almost straight and parallel to the sides. L. 1|-1| mm. 



In running water ; rare; it has only been taken apparently at Slapton Ley, Devon, 

 by Mr. Wollaston and one or two other collectors. 



MACROmrCHUS, Miiller. 



This genus contains two species, one of which is found in North 

 America, and the other in Central and Southern Europe ; M. quadri- 

 tuberculatus very closely resembles a large Elmis, but may easily be re- 

 cognized by the tubercles on the head and thorax, the very long legs, and 

 very short antennae ; although long looked for, it was not found until 

 August 1864 by my friend Mr. J. T. Harris in the Dove near its con- 

 fluence with the Trent, about two miles from Burton-on-Trent ; it has 



