19 



for my having had the advantage of working in the British Muséum (Nat, Hist.), London, 

 where most of the génotypes are represented, it would not hâve been possible to understand 

 the exact generic Hmitations of thèse new gênera. 



In the "Siboga" collection the family Nuculanidae is represented by the two subfamilies 

 Nuculaninae and Malletiinae. The former family is represented by the Gênera Nucidana Link 

 and Yoldia Moller in this collection. Most of Iredale's new gênera of the family Nuculanidae 

 are based on groups of slightly varying species of the genus Nuculana, and in the following 

 account I treat them as subgenera of Nuculana. The species of Ntutclana in the collection are 

 referred to the genus NiLCulana., s. s. -type NiLCiLlana {Nuculana) perniila (O. F. Mliller), and 

 the subgenera Megaleda Iredale ^) — type Nuculana [Megaleda) inopinata (Smith), Thestyleda 

 Iredale ^) — type Nitcttlana [Thestyleda) rainsayi (Smith), Poroleda Tate ^) — type Nuculana 

 [Poroledd] lanceolata Tate, and Ledella Verrill and Bush *) — type Nticulana [Ledella) niessa- 

 nensis (Seg.). 



1. NtLculana [Nticuland] conf^Lsa (Hanley). 



1833. Niicula Pella Sowerby (non Linn.), Conch. lllustr. Cat. Nucidae, p. 3, fig. 6. 



1860. Leda Confusa Hanley in Sowerby Thés. Conch., III, p. 119, pi. CCXXVIII, fig. 85. 



1871. Laeda confusa Sowerby in Reeve Conch. Icon., XVIII, pi. V, fig. 24bis. 



1882. Leda confusa Dunker, Ind. Moll. Mar. Japon., p. 338. 



1884. Leda confusa Grasset, Ind. Test. Viv., p. 294. 



1890. Leda confusa Paetel, Cat. Conch. Samm., III, p. 223. 



1906. Leda confusa Owston, Japan. Loochooan Shells, p. 32. 



The "Siboga" spécimens, which I refer to N. (iV.) confttsa agrée in ail respects with 

 spécimens from the China Sea in the British Muséum (Natural History), London. 



Distribution : — Sowerby gives "Japan and China Seas" as the range of this species. 



The "Siboga" collected shells in the Bay of Nangamessi, Sumba (St. 53, up to 36 mètres), 

 in Kambaragi Bay, Tanah Djampeah (St. 64) and in Macassar Strait and surroundings (St. 71). 



2. Nuculana {Nziculaiia) siôogai sp. nov. (Plate I, figs. 17, 18). 



The species is closely allied to N. (iV.) conftisa (Hanley) ^), but is easily distinguished 

 by its shell being much more inflated, the more pointed rostrum, both séries of the hinge-plate 

 more arched and more extensive, and the sculpture consisting of finer striae. 



Measurements of the Holotype : from St. 178: — Length 14.5 mm., height 8.5 mm., 

 diameter 6 mm. 



Habitat: — ■ The "Siboga" Expédition trawled a good séries of this species from St. 52 

 (9°3^4S., ii9°56'.7 E., 959 mètres), St. 156 (o°29'.2 S., 130° 5^.3 E., 469 mètres), St. 178 

 (2°4o'S., i28°37^5E., 835 mètres) and St. 300 (io°48'.6S., i23°23^iE., 918 mètres). 



Remarks : — N. [N.) siôogai is a deep-sea form as ail the spécimens of the species 

 were obtained at dephts above 450 mètres. 



i) Iredale, T. — Rec. Austral. Mus., XVII, p. 158 (1929). 



2) Iredale, T. — ibid, p. 158 (1929). 



3) Taxe, R. — ■ Journ. Proc. Roy. Soc. N. S. Wales, XXVII, p. 186 (1894). 



4) Verrill, A. E. and Bush, K. J., Amer. Journ. Sci., (4) III, p. 54 (1897). 



5) See Sowerby, G. J. — In Reeve Conch. Icon., XVIII, Laeda., pi. V, fig. 24bis (1871). 



