i877- ^- PldCîina sella de Man, Rech. P'aun. Madagascar, etc., pt. V, Mollusques, p. lo. 



1877. Placnna sella Kobelt, Illust. Conchylienb., p. 376, pi. CX, fig. 13. 



1884. Placîina [Placenta) sella Tryon, Struct. Syst. Conch., III, p. 296, pi. CXXXI, figs. 7, 8. 



1889. Placrinema sella Morlet, L., Journ. Conchyliol., XXXVIII, p. 161. 



1890. Placuna sella Paetel, Cat. Conch. Samm., III, p. 244. 



1891. Placuna sella Fischer, P., Bull. Soc. Hist. Nat. d'Autun, IV, p. 208. 

 1905. Placuna sella Hidalgo, Cat. Filip., p. 386. 



1909. Placuna [Placunenia) sella Lynge, D. Kgl. Dansk. Vidensk. Selsk. Skr. Nat. -Math. 



(7) V, p. 108. 



1910. Placuna sella Dautzenberg, Bull. Inst. Oceanogr., N" i6r, p. 3. 



1929. } Placuna sella Dautzenberg, Faun. Colon. Français., III, fasc. 4, p. 558. 



P . {E.) sella, the Saddle Oyster, has a very wide distribution in the Pacific Area, but 

 the authentic records of its occurrence in the Indian Océan do not extend west of the Merofui 

 Archipelago, de Man's record of this species from Madagascar is open to doubt, as leaving aside 

 Dautzenberg's références to the species which are based on de Man, I hâve not been able to 

 find any spécimens in the collections examined by me or any other records of the species 

 from this area. 



In the "Siboga" collection the species is represented by a magnificent shell, about 200 mm. 

 in diameter collected from the coral reef at Sanana Bay, east coast of Sula Besi (St. 193). 



Family Arcidae. 

 Genus Area Lamarck. 



The question of the génotype of Area s. s., is still a matter for discussion. I had finished 

 the writing up of my results on the Arcidae of the "Siboga" collection long before I came 

 across Stewart's valuable contribution to this very intricate question, and as is discussed further 

 on, I hâve followed Cox in accepting Children's désignation of Area torhiosa (Linn.) as the 

 génotype of Area s.s.^ but I am more inclined now to accept Schumacher's earlier désignation. 



For the sake of completeness I hâve treated the synonymies of the various subgenera 

 of this family at greater length than has been done for the other familles of Pelecypods discussed 

 in this report. 



Subgenus Navicula Blainville. 



1825. Navicula Blainville, Dict. Sci. Nat., XXXIV, p. 319. 

 1927. Navicula Cox, Rept. Palaeontol. Zanzibar, p. 93. 



In view of no earlier génotype of Area s. s., having been selected and Children ^) 

 definitely' designating A. torhiosa (Linn.) as its génotype in 1823, Cox has revived Blainville's 

 name Navicula for what had usually been accepted as Area s. s. The génotype would be A. 

 (iV.) noae (Linn.). 



i) Children, J. G. — Quart. Journ. Sci. Lit. Arts, XIV, p. 319 (1823'). 



