45 



some of the radial ribs are more marked and prominent. Ail the spécimens are without the 

 lamellose epidermis. The measurements (in millimètres) ofthe shells are: — 



Length 19.5 21 25.8 



Height 10.8 II. 9 13.3 



Diameter .... 8.9 8.8 10.6 



Distribution: — The "Siboga" Expédition collected spécimens of this species at St. 49 

 (8°2o'.5 S., ii9°4'.5 E.), in Du-roa Strait, Kei Island (St. 257) and St. 310 (8° 30' S., 11 9° 7^.5 E.). 



5. Arca {Barbatia) pazihtcciana Tapperone-Canefri. (Plate I, figs. 58, 59). 



1875. Barbatia Paulucciana Tapparone-Canefri, Ann. Mus. Civ. Stor. Nat. Genova, IX, p. 292. 



I do not agrée with Lamy ^) that Tapparone-Canefri's species A. paulîtcciana from New 

 Guinea is based on spécimens of A. nivea. There are in the "Siboga" collection a single left 

 valve dredged on the bank between the islands of Bahuluwang and Tambolungan, South of 

 Saleyer (St. 66) and 2 shells collected at Anchorage near Seget, West entrance to Selee Strait 

 (St. 163), which agrée in ail particulars with the description of A. patihicciana by Tapparone- 

 Canefri. A very young shell dredged at Banda Anchorage (St. 240) is also to be referred to 

 this species. 



In my opinion the species is more closely allied to A. decussata Sow. than to A. nivea 

 Dillwyn, and is distinguished by the straight upper margin with very angulated corners, the 

 prominent umbones situated in the anterior half of the shell, and the sculpture consisting of 

 binodulose radial ridges on the greater part of the middle of the shell ; on the area behind the 

 carina and in front of the umbonal ridge the ridges bear small, low, ovoidal nodules which give 

 the ridges a moniliform appearance. I figure one of the shells from St. 163. 



6. Arca {Barbatia^ ftcsca Bruguière. 



1685. Pectimculus e ftisco rufescens Lister, Hist. Conch., pi. CCXXXI, fig. 65. 



1742. Musculus striatiis etc. Gualtieri, Ind. Test., pi. XC, fig. B. 



1784. Arca bicolorata Chemnitz, Conch. -Cab., XI, p. 243, pi. CCIV, fig. 2007. 



1789. Arca fusca Bruguière, Encyclopéd. Méthod., I, p. 102. 



1790. Arca barbatia var. y. Gmelin, Syst. Nat. (éd. XIII), p. 3 307. 

 1798. Arca amygdaliim testitm Roding, Mus. Boltenianum, p. 175. 

 1802. Arca fusca Bosc, Hist. Nat. Coq., III, p. 129. 



1817. Arca bicolorata and A. fusca Dillwyn, Descr. Cat. I, pp. 230, 231. 



18 19. Arca fusca Lamarck, Anim. sans Vertèb., VI, p. 39. 



1825. Arca fusca Sowerby, Cat. Tankerville, p. 18. 



1835. Arca ftsca Deshayes in Lamarck, Anim. sans Vertèb., VI, p. 466. 



1843. Arca fusca Hanley, Rec. Biv. Shells, p. 154. 



1844. Arca fusca Reeve, Conch. Icon., II, Arca, pi. XII, fig. 82. 



1845. Arca fusca Catlow & Reeve, Conch. Nomencl., p. 49. 



1848. Arca fusca Nyst, Mém. Acad. Roy. Belgique, XXII, p. 30. 



1849. Arca cruciata Philippi, Abbild. Beschreib. Conch. III, p. 87, Arca, pi. V, fig. 7. 

 1853. Barbatia fusca Môrch, Cat. Yoldi, II, p. 40. 



1857. Arca [Barbatia) fusca Adams, H. & A., Gen. Rec. MolL, II, p. 534. 



i) Lamy, E. — Jouni. Conchyliol., LV, p. 64 (1907). 



