209 



Distribution : — M. {M.) artensis was described froni New Caledonia. 



The "Siboga" Expédition collected shells of this species at Banda Anchorage (St. 240). 



3. Mactra {Mactrd) inaeçualis Reeve. 



1854. Mactra inaequalis Reeve, Conch. Icon., VIII, Mactra, pi. XVII, fig. 87. 



1855. Mactra inaequalis Deshayes, Proc. Zool. Soc. London (vol. for 1854), p. 64. 



1856. Trigonella inaequalis Adams, H. & A., Gen. Rec. MolL, II, p. 376, 

 1868. Trigonella inaequalis Conrad, Amer. Journ. Conch., III, p. 37. 



1884. Mactra inaequalis Weihkauff in Martini-Chemn., Conch. -Cab. (N. F.), XI (2), Mactra, 

 p. 106, pi. XXXVI, fig. I. 



I refer with some doubt a number of young shells from the Bay of Badjo, west coast 

 of Flores, to Reeve's species Âd. {M.) inaeqtialis. Thèse shells are smooth, transversely ovate 

 to subtriangular in outline, inequilateral with the anterior side somewhat longer than the posterior, 

 obtusely rounded anteriorly and angulate posteriorly. The shells are of a yellowish colour. 



Distribution : — M. {M.) inaequalis was described from the China Sea. 



The "Siboga" spécimens were collected in the Bay of Badjo, west coast of Flores (St. 50). 

 The largest spécimen is 16 mm. long, 11 mm. high, 6 mm. maximum diameter. 



4. Mactra {Mactra) mera Reeve. 



1854. Mactra antiquata (non Spengler) and J/. ;/^^r(7: Reeve, Conch. Icon., VIII, Mactra, "^X.VX, 



fig. 22, pi. XVI, fig. 82. 

 1854. Mactra mer a Deshayes, Proc. Zool. Soc. London (vol. for 1853) p. 16. 

 1856. Trigonella niera Adams, H. & A., Gen. Rec. Moll., II, p. 376. 

 1868. Trigonella mer a Conrad, Amer. Journ. Conch., III, p. 38. 

 1881. Mactra antiquata (non Spengler) Weinkaufif in Martini-Chemn., Conch. -Cab. (N.F.) XI, (2), 



Mactra, p. 41, pi. XIII, figs. 4, 5. 

 1884. Mactra mera Weinkauff, op. cit., p. 109, pi. XXXVI, fig. 7. 

 1914. Mactra mera Smith, Proc. Malacol. Soc. London, XI, p. 144. 



I agrée with Smith that Mactra mera Reeve is quite distinct from J/. a;2^2'^?/a^<3; Spengler ^). 

 It has, however, been confused with the latter species and recorded by Reeve, Weinkauff and 

 probably other authors. 



Lamy ^) has certainly misunderstood Reeve's M. mera^ for it is not allied to M. grandis 

 Gmelin in the synonymy of which species Lamy has included it. 



Smith in the paper cited has well summarized the distinguishing characters of the species. 



Distribution : — M. {M.) mera was described from the China Sea, but has since been 

 recorded from the Australian waters, from round Bornéo and Singapore. 



In the "Siboga" collection there are shells of this species from the Bay of Labuan Tring, 

 west coast of Lombok (St. 19) and Dobo, Aru Islands (St. 272). 



5. Mactra {Mactrotoma) aspersa Sowerby. 



1825. Mactra aspersa Sowerby, Cat. Tankerville, p. 7, Appendix, p. li. 

 1828. Mactra tenera Wood, Ind. Test., Supplément, p. 4, pi. I, fig. /\b. 



i) Spengler, L. — Skrivt. Nat. Selsk., V, p. 102 (1802). 



2) Lamy, E. — Journ. ConchylioL, LXIII, pp. 234, 235 (1917). 



SIBOGA-EXPEDITIE LIIIC. , 27 



