21 



6. Nuculana {JVîicîilana) approximans sp. nov. (Plate I, figs. 25, 26). 



Shell resembling N. ventricosa (Hinds) ^) from the Strait of Malacca, but less ventricose, 

 more elongate, ventral margin less arched, umbones more tumid, lunule less excavated and the 

 sculpture coarser. 



Measurements of Holotype : — Length 16.5 mm., height 8.8 mm., diameter 6.4 mm. 



Habitat: — The "Siboga" Expédition dredged a few spécimens of iV. (iV.) approximans 

 in the Western Entrance of the Samau Strait (St. 59, 390 mètres) and a single shell at St. 159 

 o°59'.i S., i29°48'.8E., 411 mètres). 



Remarks: — I was at first inclined to consider the spécimens described above as being 

 those of N. (tV.) ventricosa (Hinds), but after comparison with spécimens of the latter in the 

 British Muséum, I am of opinion, that the "Siboga" shells are distinct. 



7. Nziculana [Magaleda) inopinata (Smith). 



1885. Leda inopinata Smith, "Challenger" Lamellibranchia., p. 236, pi. XIX, figs. 9, 9^. 

 1906. Leda inopinata Hedley, Rec. Austral. Mus., VI, p. 214. 



1918. Nuculana inopinata Hedley, Journ. Roy. Soc. N. S. Wales, LI, Suppl., p. M. 4. 

 1929. Magaleda inopinata Iredale, Rec. Austral. Mus. XVII, p. 158. 



This interesting species was described by Smith under the name Leda inopinata from 

 ofï Sydney, Australia in 950 fathoms. There are also in the British Muséum (Nat. Hist.), London, 

 spécimens from off Sydney taken by the "Challenger" in 410 fathoms and others sent by 

 Professor Haswell from 800 fathoms. 



Iredale has recently separated this species into a distinct genus Magaleda but has not 

 published any description of it. The gênerai form of the shell is very similar to that of other 

 species of the genus Nucttlana^ but the beak is short, the surface is covered "with numerous, 

 slender, radiating lirae, some of which bifurcate towards the lower end", the lirae do not extend 

 to the beak and there are on the shell a lar^e number of concentric striae which make the 



^ & 



gênerai surface appear somewhat tessellated. The hinge is strongly developed, with 10 long, 

 acute teeth on each side, the largest tooth is the fourth from the outer edge. 



I hâve compared the "Siboga" shells with the type in the British Muséum, and can find 

 no différences between them. 



Distribution : — The type of the species and other shells hâve so far been obtained off 

 the coast of Sydney in depth of 410 — 950 fathoms. 



The "Siboga" obtained spécimens in deep-sea trawls at St. 88 (o°34'.6N., II9°8^5E., 

 1301 mètres), St. 211 (5°4o'.7 S., i20°45^5E., 1158 mètres) and St. 221 (6°24'S., i24°39'E., 

 2798 mètres). Thèse spécimens greatly extend the range of the species. 



8. Nttcîilana [Thestyleda) modica sp. nov. (Plate I, figs. 27 — 29). 



The following is a description of this new species : — Shell of médium size, thin, very 

 elongate, sharply rounded anteriorly, with very elongate beak posteriorly, margin of rostrum 

 slightly curved ; very inequilateral ; acute almost smooth umbones lying in anterior third of total 



l) See SoWERBY, G. J. — in Reeve Conch. Icon., XVIII, Laeda. pi. V, fig. 30 (1871). 



