214 118 



Gulf of Rayong, 7—10 fathoms, sand and mud (3). Between Koh Chuen and 

 Koh Chang, 15 fathoms, mud (1). Koh Kahdat, 1 — 5 fathoms, sand with stones (1). 

 Between Koh Kut and Koh Kahdat, 10 fathoms, shells (Va). 



Long. 13—33 mm. (Long. 33 mm., alt. 29 mm., crass. 12 mm.). 



Distribution: — Arafura Sea (Challenger), Port Curtis (A.Adams). 



The concentric lamellæ upon the surface are placed more closely together 

 than is indicated in Reeve's figure. Edg. Smith (loc. cit.) gives an excellent and 

 exhaustive diagnosis of this comparatively large and beautiful species, which strangely 

 enough, has hitherto been obtained from so few localities. 



Semele casta, A. Ad. 



Se77ie;e casta, A. Adams, Proc. Zool. Soc. London, XXI, 18Ö3, p. 96, No. 15. 

 Amphidesma casta, A.Adams, Reeve, Conchol. icon., VIII, Amphidesma, Sp. 18. 



Koh Chuen, 30 fathoms (Vs). Between Koh Chuen and Koh Chang, 15 fathoms, 

 mud (1). South-west end of Koh Chang, 1 fathom, corals (1). Koh Mak, sandy 

 coast (1). 



Long. 11 — 25 mm. 



Distribution: — Gulf of Manaar (Thurston). — Moreton Bay (Australia, 

 Strange). 



The sculpture at the umbo differs from that of the rest of the shell, the 

 distance between the first 7 — 8 concentric ribs being greater and the interstices 

 between them being nearly smooth, almost quite without the radiating sculpture 

 which is found upon the rest of the shell. 



Note. Semele Jukesi, A. Ad., and Semele exarata, Ad. & Reeve, have been 

 taken at Singapore in shallow water by Mr. Sv. Gad. 



Theora lata, Hinds. 



(PI. IV, Figs. 9-11). 

 Neœra lata. Hinds, Proc. Zool. Soc. London, XI, 1843, p. 79. 

 Theora — — H. & A. Adams, Gen. of rec. Moll., II, p. 370, pi. 97, fig. 5. 



— — — Hidalgo, Fauna malacol. de 1. isl. Filipin., II, 1903, p. 71, No. 146. 

 Neœra fragilis, A. Adams, Proc. Zool. Soc. London, XXIII, 1855, p. 226, No. 25. 

 Tlieora — — Ann. and Mag. Nat. Hist., 1S(!4, p. 209. 



— — — Hedley, Proc. Linn. Soc. New South Wales, 1901, XXVI, p. 706, pi. 34, figs. 4— 6. 



Sound of Koh Chang, 3—5 fathoms, soft clay ("'/i:). The strand off the Mangrove 

 at the station on Koh Chang ('/a). Between Koh Kut and Koh Kahdat, 10 fathoms, 

 shells (5). North of Koh Kong, 8 fathoms, mud (15). 



Long. 3'5— 20 mm. 



Distribution: — Gulf of Manaar. — Philippines, Niegata (Japan), Cardvvell 

 (Queensland), Moreton Bay, Lane Cove (Sydney). 



After having compared in the British Museum, T. lata, Hinds, with T. fragilis, 

 A. Ad., I see no reason for separating these two forms and making distinct species 

 of them. 



