OF NEW ZEALAND. 73 



besides the longitudinal groove, bears a considerable depression behind, 

 the sides of which are rather acutely elevated, and converge towards the 

 hind coxse. 



The posterior femur of the male is not greatly, though distinctly 

 enough, dilated, and, near the apex, is abruptly produced in the form of 

 a large, acute tooth ; in H. duplex it is gradually and strongly dilated 

 and angulated, so that the form is quite different ; the intermediate tibia 

 is very obviously arcuated and slightly flexuose, and the anterior is 

 excised and angulated, almost acutely dentate, near its apex. 



Length, 2\\ breadth, i| lines. 



Described from two pairs found at Marsden Point, Whangarei 

 Harbour. 



139. H. (?) nitidicornis, //.i-. j?^^^' subovate, rather short and 

 thick, biconvex; rather glossy, variegated in colour; the head, front and 

 sides of the thorax, as well as the sides, apex and base of the elytra 

 being reddish-testaceous-brown, the rest of the body pitchy-brown ; the 

 antennfe are shining and yellowish, the legs testaceous, with the thighs 

 infuscate, and the four anterior tarsi are blackish and shining. 



Head finely punctured, with the front margin of the epistome a little 

 elevated and smooth. ProtJwrax short, not so wide as the elytra at the 

 base, narrowed anteriorly, with produced front angles, the sides are 

 finely margined and very little rounded, and the base is obliquely trun- 

 cated towards the sides ; its surface is finely but distinctly and moder- 

 ately closely punctured. Elytra obovate, scarcely so convex as the 

 metasternum, finely margined ; its punctation is very similar to that of 

 the thorax, each bears an indistinctly impressed longitudinal, and scant, 

 excessively fine, pubescence. The legs are rather long and stout ; the 

 four front tarsi are dilated, the joints of the middle pair are distinctly 

 longer than broad ; those of the anterior less so, the third is rather 

 large, oblong, with rounded angles, and superficially excavated near the 

 apex for the minute apical joint, which scarcely protrudes beyond the 

 extremity of the third ; the posterior are compressed and densely 

 ciliated. 



The front coxa are elongated and separated by the narrow prosternal 

 process ; the mesosternum is very short and somewhat concave along the 

 front ; and the metasternum is large, somewhat elevated in the middle, 

 with a fine longitudinal sulcate, two slightly elevated lines behind in 

 front of the coxse, and, with the exception of the smooth space behind, 

 punctate. The abdomen is punctured. The third joint of the antennae 

 is a little longer than the contiguous. 



Length, 2% lines ; breadth, li, nearly. 



I found two examples of this distinct form near Mr. Munro's house, 

 Marsden Point. 



It does not correspond apparently with any of the genera in Lacor- 

 daire's work, being differentiated by the minute apical joint of the four 

 front tarsi, &c. ; but as Dr. Sharp is engaged with the preparation of a 

 systematic work on the water-beetles of the world, and a similar form 

 occurs in Australia, he, no doubt, will have made a new generic name 

 for it. For the present, therefore, I call it a Hydroporus. 



K 



