624 EDGAR A. SMITH. 
330. Arca (Barbatia) lacerata, Linn. 37,//. II. 
331. Arca (Barbatia) lima, Reeve, 37,//. II, V, IX, XIV, XV. 
332. Arca (Barbatia) tenella, Reeve, 37,//. I, IX, XV. 
Family CARDITIDAE. 
333. Mytilicardia variegata, Bruguiére (Cardita variegata, Reeve, 37, 1.) I, EXE EXcIe OVE 
Family GALEOMMIDAE. 
334. Galeomma formosa, Deshayes, 40,),//7. XIV. 
335. ‘Thyreopsis coralliophila, H. Adams, 2. II. 
In this remarkable genus the mantle is united ventrally, with a small anterior slit for the 
passage of a small pointed foot, and a very minute anal opening behind, near to which the 
surface is somewhat scabrous or minutely papillose. There is a narrow free fold of the mantle 
bordering the margin of the valves which are thickened within and gives rise to a delicate riblet 
which extends across the inner surface of each valve from a point near the middle about half 
way towards the umbo'. Only faint traces of adductor scars are visible and probably the free 
edge of the mantle above referred to is the principal means of attachment to the shell. It does 
not appear as if it would be reflected upon the exterior of the shell when living. In a form 
where the valves are permanently more or less spread out almost horizontally, the animal being 
too large for them to close, adductor muscles would be of little service, and therefore we might 
expect to find them but feebly developed. The shell is of a purplish tint within and without, 
except towards one end, which is white. The exterior is excessively finely concentrically striate 
and microscopically radiately striate and the inner surface of the valves appears to be minutely 
pitted. The dorsal margins are thickened within and the ligament is attached in a depression of 
this thickening immediately beneath the minute, glossy, convex, boss-like umbones. 
Family TRIDACNIDAE. 
336. Tridacna cumingii, Reeve, 37, X/V. IX. 
Family CARDIIDAE. 
337. Cardium leucostoma, Born, 37,//7. IX. 
338. Cardium nebulosum, Reeve, 37, //. II. 
339. Cardium maculosum, Wood, 37,//. III. 
340. Cardium levisulcatum, n. sp. (Pl. XXXVI. figs. 25, 26). IX. 
Testa irregulariter quadrata, inaequilateralis, alba, mediocriter convexa, latere antico brevi, 
rotundato, postico oblique curvatim truncato, multo majori, margine ventrali late arcuato; valvae 
radiatim anguste sulcatae quam costis multo angustiores; costae planiusculae, circiter 25, quarum 
1 This riblet is only feebly indicated in Adams’s type in the British Museum by a slight sinuation of the 
margin at that point. 
