24 



backwards ; hinge-plate strong, with 12 — 14 teeth on both anterior and posterior séries. Shell 

 of a pale straw colour ; nacre shining white. 



Measurements of Holotype : — Length 6.1 mm., height 4.1 mm., diameter 3.7 mm. 



Habitat : — a few spécimens of N. (? L.) discrepans were dredged in Madura Bay in 

 southern part of Molo Strait between depths of 69 — 91 mètres (St. 51). 



Remarks : — I hâve some hésitation in assigning this species to the subgenus Ledella 

 Verrill and Bush ^), which, as originally defined, appears to be a composite genus. It may, 

 however, be restricted to small ovate, moderately swollen species with a short rostrum and 

 having the shell smooth or evenly sculptured with low concentric ridges or striae. The type of 

 Ledella is A*^. (Z.) messanensis (Seg.) and it was proposed to replace the preoccupied name 

 yunonia of Seguenza. 



Genus Yoldia Môller. 



1842. Yoldia Môller, Ind. Moli. Groenlandiae, p. 18. 



1858. Yoldia Adams H. & A., Gen. Rec. Moll., II, p. 548. 



1860. Yoldia Hanley, in Sowerby Thés. Conch., III, p. 106. 



187 1. Yoldia Sowerby, in Reeve Conch. Icon., XVIII, Yoldia, pi. I (explanation). 



1886. Yoldia Fischer, P., Man. Conchyliol., p. 986. 



1897. Yoldia Verrill & Bush, Amer. Journ. Sci., (4) III, p. 55. 



1898. Yoldia Dali, Trans. Wagner Free Inst. Philadelphia, III, p. 594. 



1925. Yoldia Woodring, Miocène Molluscs from Bowden, Jamaica, Pelecypods etc., p. 21. 

 1930. Yoldia Stewart, Spécial Publication Philadelphia Acad. Nat. Sci., N" 3. p. 59. 



Stewart has fully discussed the question of the génotype of Yoldia in the work cited 

 above, and I agrée with him that there can be no question about the type being Yoldia arctica 

 Môller = Y . hyperborea (Gould). 



The subgeneric divisions of Yoldia suggested by Verrill & Bush and others are not 

 satisfactory and I, therefore, propose leaving thèse out of considération in the following account. 



I. Yoldia lepidula A. Adams. 



1856. Yoldia lepidula Adams, A., Proc. Zool. Soc. London, p. 50. 



1858. Yoldia lepidula Adams, H. & A., Gen. Rec. Moll., p. 548. 



1860. Leda lepidula Hanley in Sowerby Thés. Conch., III, p. 137, pi. CCXXVI ^), fig. 6. 



1860. Nucula lepidula Reeve, Elem. Conch., II, p. 96. 



1871. Yoldia lepidula Sowerby, Conch. Icon., XVIII, Yoldia, pi. II, fig. 7. 



1890. Yoldia lepidula Paetel, Cat. Conch. Samm., III, p. 226. 



1906. Yoldia lepidula Melvill & Standen, Proc. Zool. Soc. London. p. 792. 



I hâve compared the "Siboga" shells with spécimens of Y. lepidula from round Bornéo, 

 and can find no différences between them. 



Distribution: — Y. lepidula has been recorded from Bornéo to Persian Gulf. 



The "Siboga Expédition" dredged shells of this species from St. 2 (7° 25' S., ii3°i6'E., 

 56 mètres), St. 4 (7° 42' S., ii4°i2'.6E., 9 mètres) and St. 319 (6° 16'. 5 S., ii4''37'E., 82 mètres); 

 ail thèse stations are in the Java Sea. 



i) Verrill, A. E. anJ Bush, K. J. • — Amer. Journ. Sci., (4) III, p. 54 (1897). 

 2) This plate bears the wrong number 223 instead of 226. 



