232 136 
towards the anterior end. The dorsal margin descends abruptly on both sides, in 
front in an almost straight line, and at the back somewhat convexly. The ventral 
side is decidedly curving. The surface is covered with close-set, fine, concentric ribs, 
all of which do not, however, pass entirely round the valve, but are most of them 
incomplete and inserted irregularly between each other. Upon the anterior ‘and 
posterior sides these ribs are crossed by fine radiating grooves which make the 
surface granulated at these places; these radiating grooves are at different distances 
apart and are most evident at the anterior end. At the upper part of the middle 
of the valves, somewhat below the beaks, at the point where the valves are most 
convex, the concentric ribs disappear and a bare glossy spot is formed. The lunule 
is large and lanceolate, circumscribed by a distinct impressed line, not affected by 
the radiating sculpture, but merely striated by fine lines of growth; a well-defined 
area does not occur. The interior of the shells is smooth, white and glossy. In 
the right valve there are three cardinal teeth of which the central is triangular;, 
the anterior is small, and from it proceeds a lamellar tooth which is situated 
between the lateral tooth and the upper margin which is double. In the left valve 
there are also three cardinal teeth; the posterior is the smallest, it is compressed, 
narrow and acute. Each valve has an anterior lateral tooth, oblong, compressed 
and triangular, parallel with the upper margin and separated from it by a deep 
groove. The inner ventral margin is flat. 
Long. 4 mm., alt. 4 mm., crass. 2°5 mm. 
Between Koh Rin and Cliff Rock, 15 fathoms (*/2). Gulf of Rayong, 7—10s 
fathoms, sand and mud (*/2). Koh Chuen, 30 fathoms (*/2). W. of Koh Chuen, 
mud mixed with clay (*/z). S. of Koh Chuen, 30 fathoms, shells ("/2). S. of Koh 
Samit, 20 fathoms, mud (2 + !°/2). South-east of Koh Samit, 13—14 fathoms, mud 
mixed with sand (4/2). S. of Koh Tulu, 10 fathoms, mud mixed with sand (7/2). 
Sound of Koh Chang, 83—5 fathoms, soft clay (‘/2). W. of Koh Chang, 20 fathoms, 
mud (3 + !/2). Between Koh Kut and Koh Kahdat, 10 fathoms, shells (2 -- '/2). 
Between Koh Kahdat and Koh Kut, 6 fathoms, mud mixed with clay (**/2). S. of 
Koh Kahdat, 8—10 fathoms, mud (!/2). W. of Koh Kut, 15 fathoms, mud ('*/2). 
S. of Koh Kut, 17—20 fathoms, mud (1/2). 
This characteristic and beautiful little species is common in the Gulf of Siam; 
it is nearest related to C. nana, Mely., and C. amica, Smith, from which it is, 
however, easily distinguished. I have ventured to dedicate this species to Mr. JAMES 
Cosmo MELyitL, who, by his valuable papers, has contributed so largely to our 
knowledge of the marine Molluscan fauna of Asia. 
Circe (Lioconcha) picta, Lam. 
Cytherea picta, Lamancx, Hist. nat. d. anim. sans vert., V, 1818, p. 569, No. 33. — éd. 2, VI, 1835, p. 309, 
No. 33. 
Lioconcha picta, LaMAncK, ROMER, Malakozoolog. Blatter, IX, 1862, p. 144, No. 13. 
Circe -- REEVE, Conchol. icon., XIV, Circe, Sp. 42. 
Cytherea (Lioconcha) picta, LaMAnck, ROMER, Monogr. d. Molluskengatt. Venus, I, p. 164, No. 15, pl. 45, fig. 3. 
Meretrix - Antuony, Bull. du Muséum d’Hist. Nat. Paris, 1905, p. 494. 
