180 , 84 



shell). The posterior side is somewhat higher than the anterior, and hoth are genllj' 

 rounded towards the ventral side which is straight. The very concave valve is 

 flattened in the middle, so that towards the sides rounded keels are formed in 

 passing to the anterior and posterior ends. The surface is somewhat glossy, and 

 is rough owing to irregular, concentric, coarse lines of growth. The interior of 

 the valve is white and slightly glossy. In the left valve, just under the apex, are 

 two cardinal teeth of which the anterior one is the smaller; the internal ligament 

 is situated immediately behind the posterior tooth. There is also a small ])osterior 

 lateral tooth which is very slightly developed. 



Long. 6 mm., alt. 3-5 mm., crass. 37 mm. 



South of Koh Tulu, 10 fathoms, mud mixed with sand QI-j). 



Unfortunately, the Danish Expedition obtained only the left valve described 

 above; it is, however, very characteristic in form. 



Kellya lilium n. sp. 



(PI. Ill, Figs. 25-26). 



The shell is oblong-ovate, white, semitran.sparent, dully glossy, rather flat and 

 thin. The upper margin slopes from the umbo gradually down on both sides, most 

 sharply towards the posterior end, which is somewhat more acutely rounded than 

 is the anterior. The ventral side is slightly convex. The umbones, which are not 

 especially prominent, are situated somewhat towards the posterior end. At the apex 

 the embryonic shell remains as a small, globular, smooth tubercle. Upon the sur- 

 face the lines of growth appear as irregular, coarse slriæ. In the shell-substance 

 are seen, both internally and externally, close-set, fine lines which radiate from the 

 umbo. The interior of the valves is white and glossy. The hinge-teeth are very 

 slightly developed in comparison to the size of the valve; under the apex and some- 

 what in front of it there is, in the right valve, a well-developed, prominent, flat, 

 triangular and acute cardinal tooth, and a small posterior tooth, more slightly 

 developed; between these two teeth there is a triangular pit. The left valve has 

 an anterioi-, long, rather stout, triangular tooth, at the hinder border of which, just 

 below the beak, is a small insignificant rudimentary tubercle (in other Kellijn- 

 species this is developed into a fairly large tooth). Upon the posterior upper 

 margin there is a rather small triangular tooth, at the hinder border of which the 

 ligament is attached; between the cardinal teelh there is a triangular space. The 

 muscular scars are fairly distinct. 



Long. 13 mm., alt. 9 mm., crass. 5 mm. 



The sound of Koh Chang, 3-5 fathoms, soft clay {V^). N. of Koh Kut, 10 

 fathoms, mud (^/l)- 



In outline and external appearance this species somewhat resembles Abra 

 alba. Wood. 



