REPORT ON THE LAMELLIBRANCIJIATA. 225 



This species is quite distinct from Trigonia lamarckii from. Port Jackson, difteriug 

 .not only in sculpture but also in form, the emargination of the posterior truncated side 

 being constai.t in a'l specimens. It is only known at present as an inhabitant of the 

 region between North Australia and New Guinea. 



Family N u c u l i d .^i;. 



Nucithi, Lamnrck. 

 Nucida obliqua, Lamarck. 



Nucula ohliqua, Lamarck, Hist. Nat. Anim. sans vert., ed. 2, vol. vi. p. 505. 

 Nucula ohliqua, Hanlcy, in Sowerby's Thes. Couch., vol. iii. p. 156, pi. ccxxx. fig. 150. 

 Nucula ohliqua, Chenn, Manuel Conch., vol. ii. p. 179, fig. 897, from type teste Hauley. 

 (Non Nucula ohliqua, Sowerby, Conch. 111., fig. 21 ; and Hanley, Cat. Recent Biv. Shells, 

 p. 171, pi. XX. fig. 9 = Nuetila grarji, d'Orbigny.) 



Habitat. — Station 188, south of New Guinea, at a depth of 28 fathoms; also 

 Torres Strait, 3 to 11 fathoms (Challenger); Arafura Sea, North Australia, 32 to 

 36 fathoms (Dr. Coppinger of H.M.S. "Alert") ; Cap aux Iluitres, Australia (Peron teste 

 Lamarck). 



This appears to be the largest living species of the genus Nucula. A single valve from 

 the Arafura Sea collected by Dr. Coppinger is 28 mm. in length and 20 high. At this 

 age it is a strong solid shell, internally thickened along the ventral margin, having deep 

 muscular impressions. The hinge-teeth are long, acute, keeled on the sides towards the 

 umboues, and excavated exteriorly. In the largest specimen there are twenty-six on the 

 anterior margin and only seven posteriorly, and in another example of half the length 

 there are twenty in front and five behind. The ligament-pit is horizontal, deep, and 

 narrow. The internal nacre is whitish, or tinted with pale brown or red. The 

 excessively fine crenulation of the margin described by Hanley is preserved in the oldest 

 specimens. 



Nucula nitidula, A. Adams. 



Nucula nitidula, A. Adams, Proc. Zool. Soc. Lond., 1856, p. 51. 



Nucula nitidula, Hanley, in Sowerby's The-. Conch., vol. iii. p. 150, pi. ccxsix. tig. 142. 



Nucula nitidula, Sovrerby, Conch. Icon., vol. xviii. pi. iv. fig. 27. 



Nucula nitirhda, Huttun, !Man. New Zeal. Moll., p. 16t. 



Habitat. — Station 167a, Queen Charlotte Sound, Cook Strait, New Zealand, in 10 

 fathoms ; mud. 



This species is remarkable for its oblique narrow form, the almost rectilinear or very 

 slightly curved hinder dorsal slope, and its prominent defined lunular space. 



(zool. CH.\LL. EXP. — PART XXXV. — 1885.) Mm 29 



