83 179 



dorsal margin, from which it is separated by a narrow groove which receives a 

 corresponding loolh in liie other valve. The internal ligament is small and is 

 located just beneath the apices and behind Ihe cardinal teeth in both the valves. 

 The interior is dully pink. 



Long. 9 mm., alt. 85 mm., crass. 5 mm. 



Between Koli Mesan and Koh Chuen, 25 — 38 fathoms p/s). 



Kellya rosea somewhat resembles A', rotunda, Desh., but is easily distinguished 

 from it by ils pink colour, and by the absence of the glossy iridescent surface of 

 A', rotunda; neither is it so convex, and the valves are more gently and regularly 

 rounded than in rotunda. For the rest, the species belonging to the genus Kellya 

 vary considerably; not onlj' do young and old individuals often differ greatly in 

 form, but also full-grown specimens may often be very different in both form and 

 outline. Young individuals of A', rosea (and also of other species) are usually longer 

 in proportion to their height, and the ventral margin is straighter, than is the 

 case in larger specimens. 



Kellya vitrina n. sp. 



(H. Ill, Figs. 21-22). 



This little species is hyaline, and somewhat silver-shining, thin, rather flat 

 and triangular in Ibrm. The umbones are situated at about the middle of the 

 longitudinal axis and the upper margin slopes gradually down on each side. The 

 anterior and the posterior ends are rounded, the ventral side is fairly straight, and 

 somewhat concave in the middle. The surface is smooth and ornamented with 

 fine lines of growth; the concavity mentioned above extends from the ventral side 

 upwards beyond the middle of the valves as a slight depression and disappears 

 gradually towards the umbones. The interior of the valves is highly glossy, the 

 hinge is composed of a single little posterior cardinal tooth in the right valve and 

 two strong diverging teeth in the left, between which tlie internal ligament is 

 situated. The right valve has, moreover, two long lateral lamellæ, one on each 

 side, parallel with and closely along its dorsal margin; and in the left valve is one 

 solitary, very slightly developed lateral lamella directly upon the anterior dorsal 

 margin. 



Long. 2-Ö mm., alt. 2 mm., crass. 1 mm. 



Koh Chuen, 30 fathoms (1). 



In spite of its small size this characteristic species is undoubtedly full-grown; 

 in outline it somewhat resembles Pijthina üesliayesiana, Hinds. 



Kellya elongata n. sp. 



(1^1. Ill, Figs. 23-24). 

 This s|)ecies is oblong-ovate and convex, and opaque white in colour. The 

 umbones which are situated towards the anterior end are slightly elevated above the 

 hinge-line and terminate in obtuse, circular, glossy, shield-like bosses (the embryonic 



23" 



