47 

 7- Arca [Bardatia) fiisca Brug'uière, var. rodaizi Dunker. 



1795. Arca bicolorata Chemnitz, Conch.-Cab., XI, p. 243, pi. CCIV, fig. 2007. 



1848. Arca bicolorata Nyst, Mém. Acad. Roy. Belgique, XXII, p. 12. 



1858. Barbatia rodatzi Dunker, Novitat. Conch., Moll. Mar., p. 89, pi. XXIX, figs. i — 3. 



1889. Arca [Barbatia) rodatzi Kobelt in Martini Chemn. Conch.-Cab., (N. F.), VIII (2), Arca, 



p. 125, pi. XXXII, figs. 3, 4. 

 1907. Arca [Barbatia) fusca (ex parte), Lamy, Journ. Conchyliol., LV, pp. 53, 54. 

 191 1. Arca [Barbatia) Rodatzi Pelseneer, "Siboga" Lamellibranches, (Anat.), p. 13. 



The ovate-oblonof and less regfular outline, the almost white inner colour of the shells 

 which is bordered by a narrow brown band only along the marg-in in the posterior part of the 

 shell and somewhat narrower hinge, are sufficient to distinguish Dunker's form as a variety 

 distinct from the typical form of A. [B.) fusca. 



Distribution : — Dunker described this form from the coast of Zanzibar. 



In the "Siboga" collection it is represented from St. 105 (6°8'N., i2i°i9'E.), Anchorage 

 off Lirung, Salibabu Island (St. 133), Wunoh bay (St. 152), Anchorage off Noimini, South 

 Coast of Timor (St. 296) and St. 310 (8° 30' S., ii9°7'.5E.). 



8. Arca {^Barbatia) obtusoides Nyst. 



1844. Arca obtusa (non Philipps) and A. obliquata (non Gray) Reeve, Conch. Icon., II, Arca, 

 pi. XII, figs. "j-j, 80. 



1844. Arca obtusa Reeve, Proc. Zool. Soc. London, p. 123. 



1845. Arca obliquata and A. obtusa Catlow & Reeve, Conch. NomencL, p. 50. 

 1848. Arca obtusoides Nyst, Mém. Acad. Roy. Belgique, XXII, p. 50. 



1851. Arca sinensis Philippi, Zeitschr. Malakozool., VIII, p. 53. 



1860. Arca obliquata and A. obtusa Reeve, Elem. Conch.. II, p. 23. 



1869. Barbatia obtusa Frauenfeld, Abhandl. Zool. -Bot. Ges. Wien, XIX, p. 886. 



1869. Arca decurvata Lischke, Malakozool. Blàtt., XVI, p. 108. 



1869. Arca decurvata and A. obtusa Lischke, Japan. Meeresconch., I, p. 148. 



1882. Arca decurvata Dunker, Ind. Moll. Mar. japon., p. 232. 



1890. Barbatia decurvatœ Paetel, Cat. Conch. Samm., III, p. 213. 



1891. Arca [Barbatia) decurvata and A. sinensis Kobelt in Martini Chemn. Conch.-Cab. (N. F.), 



Vin (2) Arca, p. 120, pi. XXXI, figs. 5, 6, p. 228. 

 1895. Arca [Barbatia) obtusa Pilsbry, Cat. Mar. Moll. Japan, p. 148. 

 1907. Arca [Barbatia) decurvata, Lamy, Journ. Conchyliol., LV, p. 73. 

 1911. Arca decurvata Pelseneer, "Siboga" Lamellibranches (Anat.), p. 11. 



After examination of the type of A. obhtsa Reeve I hâve no doubt that it is identical 

 with the form later described as A. decitrvata by Lischke, and which was based on the species 

 described and figured in "Conchologia Iconica" as A. obliquata by Reeve. It may also be noted 

 that Gray's a. obliqîiata., as has been shown by Phillippi, Krauss and others, is quite différent 

 from the species figured by Reeve under this name. There can also be no doubt that A. sinensis 

 Philippi is also a synonym of this old species. Nyst in 1 848 proposed the name obhtsoides in 

 place of the preoccupied obhtsa, but the différent workers on the family hâve adopted Lischke's 

 later name decurvata in préférence to Nyst's earlier obtusoides. 



Distribution : — A. [B.) obhtsoides has so far been recorded from Japan, Korea, China, 

 the Philippines, New Caledonia and Ceylon. In the "Siboga" Collection the species is represented 

 by a single shell taken in the Bay of Labuan Tring, West Coast of Lombok (St. 1 9). 



