832 PELECYPODA. [Protobranchia. 



meeting the convex basal margin ; posterior end short, rapidly de- 

 scending, broadly rounded towards the base. Lunule indistinct ; 

 escutcheon more distinctly marked, elliptical. Sculpture consisting of 

 microscopic radiate strise and rather faint concentric growth-lines, 

 usually with a few grooves near the margin. Epidermis thin, shining. 

 Colour chestnut at the umbones, brownish-olive farther down. Interior 

 yellowish-white, nacreous, with radiate stride on the lower half of the 

 valves. Margins finely crenate. Hinge with a narrow triangular 

 resilium, directed forward. A series of sharp teeth on either side of 

 the resilium, about 8 posteriorly and 17 anteriorly, those at the middle 

 highest. The posterior adductor scar smaller than the anterior. Pallial 

 line distinct, simple. 



Length, 8 mm. ; height, 7 mm. ; diameter, 4 mm. 



Type in the British Museum. 



Hub. New Zealand (Cuming) ; Taumaki Island, west coast of 

 South Island, in 10 fathoms (Captain Bollons) ; Dusky Sound, in 30 

 fathoms (R. Henry). 



Remarks. Distinguished from the nearly allied N. nitidula by the 

 much darker colour, the rounded, not angular, posterior end, and 

 the much more distinctly limited escutcheon and lunule. 



2. Nucula Hartvigiana, Pfeiffer, 1864. Plate 51, figs. 2, a. 



Nucula Harlvi'jiana, Pfr., Mai. Blatter, 18(54, 57. N. sulcata, A. Adams, 

 P.Z.S., 1856, 53 ; Conch. Icon., xviii, f. 10 ; Grit. List, 49 ; Mutton, 

 J. de Conch., 1878, 54 ; M.N.Z.M., 164 ; not of Brown. N. consobrina, 

 Adams and Anaas : Hutton, C.M.M., 80 ; not of Ad. & Ang. N . lacunosa, 

 Mutton, P.L.S. N.S.W., ix, 1885, 528; Medley, T.N.Z.I., xxxviii, 70. 

 N. Hnrtvir/iana, Pfr. : Suter, T.N.Z.I., xl, 353/ 



Shell small, very inequilateral, ventricose. obliquely ovate, pale 

 olive, densely concentrically sulcate. Beaks at about the posterior 

 fourth, approximate, small and not much raised, directed backwards. 

 Anterior end sloping, lightly convex, sharply rounded towards the 

 rounded basal margin ; posterior end shortly rounded. Lunule in- 

 distinctly marked ; escutcheon more distinct, bounded by a slight 

 ridge on either side. Sculpture consisting of somewhat irregularly 

 spaced narrow concentric riblets, with somewhat broader interstices 

 which are adorned with radiate striae visible under a lens. Epidermis 

 thin, shining. Colour pale olive or greyish-white. Interior white, 

 pearly, with distinct fine radiate strise and crenulated margins. * Hinge 

 with a narrow triangular resilium. directed forwards. A series of 

 sharp and high teeth on either side of the resilium, 8 posteriorly and 

 14 anteriorly, decreasing in size towards the apex. Adductor-scars 

 of nearly equal size. Pallial line distinct, simple. 



Length, 7-5 mm. ; height, 6 mm. ; diameter, 4-25 mm. (type). 



Type of N. sulcata in the British Museum. 



Hob. New Zealand (Hartwig). Bay of Islands ; off Great Barrier 

 Island, in 110 fathoms ; Hauraki Gulf, at low-water mark ; Petane, 



