104 8 
Yoldia tenella, Hinds. 
Nucula tenella, Hinps, Proc. Zool. London, XI, 1843, p. 99. 
— — Hanvey, Rec. bivalve shells, p. 376, pl. 19, fig. 47. 
Leda — = — Monogr. of the fam. Nuculidw (Sowersy, Thesaurus Conchyl., III) p. 137, 
No. 56, pl. 1, fig. 15. 
Yoldia = — Reeve, Conchol. icon., XVIII, Yoldia, Sp. 4. 
Koh Chuen, 10—15 fathoms ('/z). West of Koh Chuen, soft clay and mud 
(1 + 42). East of Koh Mak, 20 fathoms, mud ('2). W. of Koh Kut, 30 fathoms, 
sand and mud (°/2). N. of Koh Kut, 10 fathoms, mud (' 2). 
Long. 4—11 mm. 
Distribution: — Singapore, Gulf of Oman (MeLviti & STANDEN). 
Yoldia serotina, Hinds. 
Nucula serotina, Hinps, Proc. Zool. Soc. London, XI, 1843, p. 99. 
Leda Sowerby, Thesaurus Conchyliorum, III, 1866, Monogr. of the fam. Nueulide by 
Haney, p. 136, No. 54, pl. 1, figs. 19—21. 
Yoldia A. ApaMs, REEVE, Conchol. icon., XVIII, Yoldia, Sp. 5. 
Leda lepida, = Proc. Zool. Soc. London, XXIV, 1856, p. 49. 
South of Koh Kut, 17—20 fathoms, mud (7/2). 
Long. 4 mm. 
Distribution: — Singapore, Gulf of Oman (MELviLL & STaNDEN). — Philip- 
pines, Borneo. 
Nuculana Belcheri, Hinds. 
(Pl. 1, Figs. 18—19). 
Nucula Belcheri, Hinps, Proc. Zool. Soc. London, XI, 1843, p 98. 
-- - Zoology of the voyage of “Sulphur.” Mollusca by Hinps. 1845, p. 63, pl. 18, 
fig. 11. 
Leda —  Hantry, Monogr. of the fam. Nuculide (SowerBy, Thesaurus Conchyl., III), p, 116, 
pl. 2, fig. 53. 
Leeda -- Reeve, Conchol. icon., XVIII, Leda, Sp. 23. 
Nuculana — —  Smiru, Proceed. Malacolog. Soc. London, V, 1908, p. 395, No. 346. 
The Sound of Koh Chang, 5 fathoms, soft clay. (‘/2). 
Long. 10 mm. 
Distribution: — Agulha Bank, Cape of Good Hope (BELCHER), off Cape 
Colony and Natal, 34—440 fathoms (Epc. Smirn). ! 
The single valve obtained from the Gulf of Siam is not full-grown, therefore, 
as may be seen in PI. 1, Fig. 19, the characteristic central keel, which extends from 
the ventral side towards the umbo, is absent at the posterior end: this agrees 
entirely with the opinion expressed by HaNntey (loc. cit., p. 117) “As the central 
keel does not extend to the umboes, it is probably wholly absent in the fry.” 
' On South African Marine Mollusca. (Annals of the Natal Government Museum. Vol. I, p. 1, 1906). 
