BIVALVIA. 227 



but in the description by M. Deshayes, that author says it differs from T. crassa, Penn., 

 in having only one lateral tooth, and the concentric striae are finer ; there is no mention 

 of any insterstitial striae, nor of the thickened internal ridge on the anterior side. 

 T. obovaia, F. Edwards, ' Geol, Journ.,' No. 11, p. 49, pi. 2, fig. 2, resembles our shell 

 in outline, and may probably, when more specimens have been obtained, and it 

 becomes better know r n, be the same as T. subrotunda of Deshayes; but until a fair 

 comparison be instituted, T. 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. Ill, fig. 18, 'Phil. En. Moll. Sic.,' called T. radula, is probably this species. 



2. Tellina balaustina, Linnceus. Tab. XXI, fig. 4, a — d. 



Tellina balaustina. Linn. Syst. Nat., ed. 12, p. 1119, No. 61, 1 767- 



— — Poll Test. Sicil., vol. i, p 49, 1791. 



_ _ Phil. Enum. Moll. Sic, vol. i, p. 25 ; vol. ii, p. 21. 



— — Forbes. Report iEgean. Invert., p. 180, 1843. 



— tenuilamellosa. Nyst. et West. Nouv. Rech. Coq. Foss. d'Anv., p. 7, pi. 3, 



fig. 6, 1839. 



— — Nyst. Coq. Foss. de Belg., p. 109, pi. 4, fig. 14 a, b, 1844. 



— ovaloides. S. Wood. Catalogue, 1840. 



Lucina balaustina. Payr. Cat. Moll. Cors., p. 43, pi. 1, figs. 21, 22, 1826. 



Spec. Char. Testa transversa, ovatd, convewd, sitbinaquilaterali, tenui ; antice 

 rotundatd, postice subangulatd ; lamellatd lamellis erectis tenuibus, distantibus ; cardir.e 

 bidentato, dentibus lateralibus magnis. 



Shell transverse, ovate, convex, slightly inequilateral, thin ; anteriorly rounded, 

 posteriorly subangulated ; covered with distant, thin, erect lamellae ; hinge with two 

 cardinal teeth and large lateral teeth. 



Length, f ths. Height, \ an inch. 



Localitg. Cor. Crag, Sutton. Recent, iEgean, 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 striae, and distant, sharp, elevated ridges or lamellae ; 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 ; 



