OF NEW ZEALAND. 1333 



development, and it has therefoie always perfectly distinct sides; 

 the cojcal lobes are broad, and the division between them extends 

 far forwards ; the supra-articular border is narrow ; the coxal lines 

 are much separated in front ; the side wings of the metasternum are 

 variable in size, but are never very small. The swimming legs are 

 well developed in some species, but are more slender in others, 

 especially in B. pacificus and other species placed near the com- 

 mencement in this arrangement of the species. The hind tarsi have 

 the joints lobed beneath externally, but to a variable extent ; their 

 claivs are often extremely unequal in length, but this is not con- 

 stantly so, and in B. pacificus they are very nearly equal ; there is 

 no file on the second ventral segment; the penultimate abdominal 

 stigma is small in comparison with what it is in Colymbetes ; the 

 prothoracic side margin is usually quite distinct, but it is very fine 

 in B. plantaris. The elytra are quite rounded at their apex. The 

 male tarsi are variable; they always bear palettes beneath, which 

 may be very minute or comparatively large ; they are more or less 

 evidently laterally compressed (very little, however, in B. plantaris}, 

 and the front claws are often very elongate, and frequently 

 unequal. 



The genus as a whole is almost or quite cosmopolitan: E. 

 pulverulosus has a remarkably wide geographical distribution in the 

 Eastern Hemisphere, and islands of the world, but is wanting in 

 the New World. 



2339. R. plantaris, n.s. (Sharp ; Aquatic Coleop., p. 608.) 

 Ovalis, sat elongatus, angustulus, nitidus, sublaevigatus, subtilissime 

 punctulatus, nullo modo reticulatus, testaceus ; pectore, abdomine, 

 et capite utrinque ad oculos nigris ; elytris nigro-irroratis, punctis 

 seriatis conspicuis, prosterno in medio minus elevato, processu sat 

 elongato, parum compresso ; metasterni lateribus brevibus ; tarsis 

 posterioribus elongatis, unguiculis valde insequalibus. 



Long., 10mm. ; lat., 5mm. 



The male has the front tarsi rather broadly dilated, and not com- 

 pressed, the fourth joint being triangular ; they are clothed beneath 

 with four series of narrow palettes, and on the basal portion with 

 short setae ; their claws are rather short and stout, and strongly 

 curved, the front one being rather shorter than the hind one ; the 

 middle tarsi are also dilated and clothed like the front feet, their 

 fifth joint is elongate, but the claws are wanting in the only speci- 

 men known. The female is unknown. 



Dunedin. Castelnau. 



2340. R. pulveruloSUS, Steph. (Sharp; Aquatic Coleop., 

 p. 609.) Ovalis, hand convexus, nitidus, subtus niger, prosterni 

 processu plus minusve dilutiore, antennis pedibusque anterioribus 

 testaceis, pedibus posterioribus piceis, supra testaceus, vertice nigro 

 rufoque variegato, thorace in medio macula transversa fusco-nigra, 

 elytris creberrime nigro-irroratis ; tarsis posterioribus haud elongatis, 



