303 



is closely allied to G. {G.) pallida (Deshayes) ^), but the nevv species is much smaller, and has 

 a more regular, more narrow and less elongate shell ; the anterior side is slightly attenuated 

 and the posterior is broadly truncated. The sculpture is more délicate ; in addition to the well 

 marked growth lines and the oblique concentric striae there are a large number of low, vertical 

 lines running in between the oblique striae. The posterior ridge is hardly marked, but in some 

 young shells there are a few low, radiating ridges on the posterior wing of the shell. The shell 

 is of a light rose colour, with a whitish periostracal covering; the nacre is shining pale with 

 a whitish margin. 



Measurements of Holotype : — Length 24 mm., height 13.2 mm., diameter 6.5 mm. 



Habitat: — The Holotype and a young paratype were collected in Sapeh Bay, east 

 coast of Sumbawa (St. 311). A young shell and some dead valves were also obtained in the 

 Bay of Badjo, west coast of Flores (St. 50) and at Saleyer Anchorage (St. 213). 



8. Gari [Garî) sibogai, sp. nov. (Plate VII, figs. 3, 4). 



The following is a description of this new species : — species of a small size ; shell 

 transversely elongate, subequilateral ; moderately inflated, thick; anterior margin narrowly rounded, 

 posterior subtruncate, ventral border slightly arcuate ; umbones subcentral, acute, directed backwards 

 and inwards; sculpture consisting of almost regular, well impressed concentric ridges up to 

 posterior area, where in middle région of shell a number of ridges unité in pairs and similarly 

 to ridges in upper and lower parts of shell curve over to form with the well developed radial 

 ridges in this area on right valve only, a beautifully decussated pattern ; on left valve posterior 

 area with only very minute concentric striae, concentric striae also developed on umbones ; hinge 

 consisting of two teeth in right and a single somewhat bifid tooth in left valve. Shells varying 

 in colour from white, orange to rose purple ; nacre of a deeper shade, shining. 



Measurements of Holotype: — Length 20.2 mm., height 9.7 mm., diameter 6 mm. 



Habitat: - Three shells of this interesting species were dredged at Banda Anchorage (St. 240). 



Remarks : — The well developed decussate sculpture on the posterior area of the right 

 valve and the almost microscopic concentric sculpture on the same area of the left valve are 

 very characteristic of the species. 



9. Gari [Gobraeus) ametkystus (Wood). 



1773. La Langue bleue Knorr, Délices des Yeux, VI, p. 22, pi. XII, fig. 2. 



1782. Tellina amethystea ex parte and T. gari Linnaei (ex parte), Chemnitz, Conch.-Cab., 



VI, pp. 79, 100, pi. X, fig. 93. 

 1788. Tellina amethystea Schroter, Conch.-Cab. Namen Reg., p. 103. 

 1788. Tellina gari Roding (non Linn.), Mus. Boltenianum, p. 186. 

 1798. Tellina gari Spengler (non Linn.), Nat. Hist. Selsk., IV (2) p. 70. 

 18 15. Solen Amethystus Wood, Gen. Conch., p. 138, pi. XXXIV, fig. i. 



18 17. Solen amethystus Dillwyn, Descr. Cat., I, p. 68. 



18 18. Psammobia caerulescens Lamarck (ex parte), Anim. sans Vertèb., V, p. 513. 

 1825. Solen Amethystus Wood, Ind. Test., p. 16, pi. III, fig. 31. 



1832. Psammobia Caerulescens Sowerby, Gen. Shells, II, fig. 3. 



i) Deshayes, G. P. — Proc. Zool. Soc. London (volume for 1854), p. 323 (1855). 



