103 199 



OiT Koh Kam, 10 fathoms, gravel ('/:;). Between Koh Mesan and Cape Liant, 

 5—9 fathoms (Vs). Between Koh Kut and Koh Kahdat, 10 fathoms, shells (^/a). 



Long. 6—9 mm. (long. 9 mm., ait. 7 mm.). 



Distribution:— Karachi, Mekran coast, Persian Gulf, Durban.' — Philip- 

 pines, Torres Strait, Flinders Passage, Viti Isis. 



Sowerby's figure in Reeve's "Conchol. icon." (pi. 41, sp. 232), which Edg. Smith 

 regards as "bad," agrees fairlj' well with the individuals from the Gulf of Siam, 

 and although it is not perfectly typical, yet it can be recognised ; besides, it agrees 

 well with Sowerby's original figure in "Thesaurus Conchyliorum." 



Tellina (Moerella) semitorta, Sow. 



(PI. Ill, Figs. 43-46). 



Tellina scmilorla, Sowerby,' Reeve, Conchol. icon., XVII, 18()7, Tellina, Sp. 221. 



— (Mœra) semitorta, Sowerby, Angas, Proc. Zool. Soc. London, 1867, p. 919. 



— if) — — Edg. Smith, Report on the Laniellibranchiatn of the Challenger 



E.\ped., p. 111. 



— (Donacilla) semitorta, Sowerby, Mei.vili. & Standen, Journ. Linn. Soc. Zool., XXVII, p. 201. 



— — — — V. Bertin, Revision d. Tellinidés, p. 263, No. 81. 



Between Koh Bin and Cliff Bock, 15 fathoms (V-i). Koh Kram, 30 fathoms (V2). 

 N. of Koh Kam, 5 fathoms, gravel (4 + 'Va). Ofi" Koh Kam, 10 fathoms, gravel ('/a). 

 Between Koh Mesan and Cape Liant, 5—9 fathoms (12). North side of Koh Mesan, 

 10—15 fathoms, stones (^/s). Gulf of Rayong, 7 — 10 fathoms, sand and mud (1 + Va). 

 Between Koh Kut and Koh Kahdat, 10 fathoms, shells ('/2). W. of Koh Kut, 15—30 

 fathoms, mud (1 + 2/.,) Koh Kahdat, 1—5 fathoms, sand (2 + %). 



Long. 2-5 12 mm. 



Distribution: — Singapore (low water, Sv. Gad). Torres Strait, Port Jackson 

 (Sydney), Watson's Bay (New South Wales). 



This species varies considerably in form; on PI. Ill, Figs. 43—46, I have 

 given several instances of this;" the sculpture, also, is very variable. Thus, for in- 

 stance, the concentric striation may be more or less close-set; and the place where 

 the less close-set, posterior striation meets the rest of the valve-sculpture is often situated 

 very far back, while in other specimens it may be at about the middle of the valve; 

 and often the more prominent lamellar sculpture upon the posterior end has al- 

 most entirely disappeared, and the sculpture is nearly uniform over the whole 

 surface of the valve. Nor is the striation, as a rule, the same on both valves. The 

 tortuosity of the posterior end of the valves, mentioned by Edg. Smith (loc. cit., p. 112), 

 is in one specimen directed towards the right, and in another towards the left. 

 Smith's statement that: "the anterior lateral teeth and the plate supporting the 

 ligament are tinged with pale-red," is not found in the specimens from the Gulf 



' Edg. Smith, Proc. Malacolog. Soc. London, vol. 5, p. 400. 



- Edg. Smith's criticism of Sowerby's figure in Reeve's "Conchol. icon." is unjustified; several 

 specimens from the Gulf of Siam have the form shown in Sowerby's figure. 



