99 195 



lion into Ihe somewhat truncated posterior side. The umbo is situated towards 

 the posterior side and the apex bends towards it. The umbo is fairly high and 

 slopes gradually downwards on both sides. The surface is covered with close-set, 

 regularly-arranged, concentric striæ; some of these terminate at the place on the 

 posterior side where they bend upwards, and only every other is continued up- 

 wards to the area which is limited by a small keel. The interior of the valve 

 is pure white; in the right valve (which alone is at hand) the lateral teeth are 

 strongly developed on each side; there are two cardinal teeth, of which the hinder 

 is the larger. The palliai sinus is large and deep, but appears very indistinctly 

 upon the glossy inner surface. 



Long. 5"5 mm., alt. 5 mm., crass. 3 mm. 



West of Koh Kut, 30 fathoms, sand, mud. 



As the left valve is not known I cannot decide with certainty whether this 

 species belongs to the subgenus Arcopagia. 



I have ventured to associate with the name of the present species that of Mr. 

 Edg. Smith, to whom malacological science is indebted for so many valuable works. 



Tellina (Merisca) Martensi n. sp. 



(PI. Ill, iMgs. 40-42). 



This shell is small, white, rather thick-valved and triangular in outline. The 

 surface is ornamented with more or less close-set, raised, concentric lamellæ, the 

 interspaces are smooth and somewhat glossy. The umbones, which are situated at 

 about the middle of the shell, are pointed and prominent, and slope rather abruptly 

 downwards on both sides. The somewhat swollen anterior end passes gradually, 

 and with rounded outline, into the ventral side which is convex and forms a rather 

 acute angle with the hinder side. The jjosterior part exhibits a slight "Tellina- 

 curvature." The interior of the valves is white and glossy. In the right valve 

 there are two cardinal teeth, and two oblong, strongly developed lateral teeth; in 

 the left valve there are no lateral teeth and of the two cardinal teeth the anterior 

 is the larger. The palliai sinus is large and deep. 



South of Koh Kut, 17—20 fathoms, mud (Va). (Singapore, 2—3 fathoms, coral- 

 reef; '"l-i). 



Long. 35 mm., all. 3 mm., crass. 2 mm. 



This little characteristic Tellina-form must be referred to Dall's section 

 Merisca of the subgenus Arcopagia; it somewhat resembles the much larger T. (Merisca) 

 crystallina, Wood, ' from South Carolina, but that species is longer, and has a more 

 decided rostrum. The specimens at hand show that the species varies considerably 

 in regard to form and the density and height of the lamellæ. I have named this 

 species aller the late Professor Ed. v. Martens, the first zoologist who gave us a 

 fauna of the Mollusca of Siam, and to whom malacological science is indebted 

 for many profound and valuable papers and works. 



' Proceed. Unit. Stat. Nat. Mus., vol. 23, 1>)00, p. ;ni, pi. 2, fig. 10. 



25* 



