BIVALVIA. 227 
but in the description by M. Deshayes, that author says it differs from 7. crassa, Penn., 
in having only one lateral tooth, and the concentric striz are finer; there is no mention 
of any insterstitial striz, nor of the thickened internal ridge on the anterior side. 
T. obovata, F. Edwards, ‘Geol, Journ.,’ No. 11, p. 49, pl. 2, fig. 2, resembles our shell 
in outline, and may probably, when more specimens have been obtained, and it 
becomes better known, be the same as 7. subrotunda of Deshayes; but until a fair 
comparison be instituted, 7. crassa can scarcely be considered as dating its specific 
existence from the Older Tertiaries. 
This species has a range in depth extending from low-water mark to below 50 
fathoms, and its favorite habitat is in gravelly sand. It is found fossil in the 
Belgian Crag, and in the newer Tertiaries of Calabria, but it is not known as a living 
species in the Mediterranean. 
Tab. II, fig. 18, ‘Phil. En. Moll. Sic.,’ called 7. radula, is probably this species. 
2. TELLINA BALAUSTINA, Linneus. Tab. XXI, fig. 4, a—d. 
TELLINA BALAUSTINA. Linn. Syst. Nat., ed. 12, p. 1119, No. 61, 1767. 
— — Poli. Test. Sicil., vol. i, p 49, 1791. 
—_ — Phil. Enum. Moll. Sic., vol. i, p. 25; vol. ii, p. 21. 
— = Forbes. Report Aigean. Invert., p. 180, 1843. 
— TENUILAMELLOSA. Nyst. et West. Nouv. Rech. Coq. Foss. d’Any., p. 7, pl. 3, 
fig. 6, 1839. 
— — Nyst. Coq. Foss. de Belg., p. 109, pl. 4, fig. 14 a, b, 1844. 
—  ovatorEs. S. Wood. Catalogue, 1840. 
Lucina BALAUSsTINA. Payr. Cat. Moll. Cors., p. 43, pl. 1, figs. 21, 22, 1826. 
Spec. Char. Testa transversd, ovatd, convexd, subinequilaterali, tenui; anticé 
rotundatd, postice subangulatd ; lamellatd lamellis erectis tenuibus, distantibus ; cardine 
bidentato, dentibus lateralibus magnis. 
Shell transverse, ovate, convex, slightly inequilateral, thin; anteriorly rounded, 
posteriorly subangulated ; covered with distant, thin, erect lamelle; hinge with two 
cardinal teeth and Jarge lateral teeth. 
Length, 3ths. Height, } an inch. 
Locality. Cor. Crag, Sutton. Recent, Aigean, Mediterranean, and British. 
Very few specimens of this delicate and pretty species have fallen to my researches, 
and those are all from one locality. The exterior is ornamented with very fine and 
numerous concentric striz, and distant, sharp, elevated ridges or lamelle; the last 
are so thin that many of them are rarely left upon the surface; the posterior side is 
the smaller, slightly truncated, or rather biangulated, with an incipient fold very far 
back; the right valve has two cardinal teeth, posterior one the larger and subbifid ; 
two lateral teeth nearly equidistant, anterior one large, the other nearly obsolete ; 
