NIAGARA GROUP 257 
Fig. 5 1. A profile or cardinal view of the preceding specimen, showing the strong elevated 
laminae for muscular attachment. 
This feature of the interior is quite peculiar, and is alone sufficient to distinguish 
the species. 
Position and locality. This species is more abundant in the vicinity of Rochester, than at 
any other locality examined. It is also common at Marshall’s mill in Sweden, and at Wolcott 
in Wayne county, and less abundant at Lockport and other western localities. In England, it 
occurs in the Wenlock Limestone, and in the same position in the Island of Gothland. 
448. 23. LEPTiENA DEPRESSA. 
Pl. LIII. riff. 6 a - l. 
Dritte Anomiten art mit breiter schlosskante. Hupscii, Naturg. des Neiderdeutschland, 1781, 
Yol. 1, pag. 15, pl. 1, fig. 7 & 8. 
Anomites rhomboidalis. Wahlenberg, Acta Soc. S. Upsaliensis, 1821, Yol. viii, pag. 65, no. 7. 
Producta depressa. Sowerby, Genera of Shells. 
— — Id. Min. Conchology, 1825, Vol. v, pag. 86, pl. 459, fig. 3. 
Producta rugosa. Hisinger, Vet. Acad. Handlingar, 1826, p. 33. 
Productus depressus. Defranc, Diet, des Sciences naturelles, 1826, Vol. xlvii, 353. 
Leptcena rugosa. Dalman, Vet. Acad. Handlingar, 1827, pag. 106, pl. 1, fig. 1. 
Leptcena depressa. Id. Ibid. pag. 107, pl. 1, fig. 2. 
Strophomena rugosa. Broun, Leth. geognostica, 1825, Vol. i, pag. 87, pl. 2, fig. 8. 
Producta depressa. Phillips, Geol. Yorkshire, 1846, Vol. ii, pag. 215, pl. 8, fig. 18. 
Productus depressus. Deshayes, 2d Edit. Lamarck An. sans vertebres, Vol. viii, p. 380. 
Leptcena rugosa and L. depressa. Hisinger, Leth. suecica, 1837, pag. 69, pl. 20, fig. 2 & 3. 
Orthis rugosa. Von Buch, Ueber Delthyris, 1837, p. 70. 
Leptcena. Fischer, Orj'ct. du Gouv. du Moscou, 1837, p. 143. 
Leptcena depressa. J. Sowerby in Murchison’s Sil. System, 1839, pag. 623 & 636, pl. 12, fig. 2. 
L. tenuistriata [?]. Id. Ibid. pag. 636, pl. 22, fig. 2 a. 
L. rugosa. Id. Trans. Geol. Soc. London, 1840, 2d series, Vol. v, pl. 56, fig. 4. 
Orthis rugosa. Eichwald, Sil. Syst. in Esthland, p. 162. 
Leptcena rugosa. Phillips, Pal. Fossils, 1841, pag. 57, pl. 24. fig. 95. 
L. depressa. De Koninck, Desc. An. Foss, de Belgique, 1842, pag. 215, pl. 12, fig. 3, 4, 5, 6 ; 
pl. 13, fig. 6. 
L. — G. B. Sowerby, Conch. Manual, 1842, pag. 71, and pag. 300, fig. 206. 
Orthis rugosa. D’Archtac and De Verneuil, Trans. Geol. Soc. London, 1842, 2d series, 
Vol. vi, part 2, p. 396. 
Strophomena depressa. Vanuxem, Geol. Rep. 3d Dist. New-York, 1842, pag. 79, fig. 5. 
S. undulata. Id. Ibid. pag. 139, fig. 3. 
S. depressa. Hall, Geol. Rep. 4th Dist. New-York, 1843, pag. 77, fig. 5 ; pag. 104, fig. 2. 
Orthis rugosa. C. F. R<emer, Rhein. Uebersgangsgebirge, 1844, pp. 85 & 90. 
Leptcena depressa. De Verneuil, Geol. Russia and the Urals, 1845, Vol. ii, pag. 234, pl. 15, 
fig. 7. 
Shell semioval or semicircular; hinge-line equal to, or extending beyond the width of the 
shell; dorsal valve having the upper part nearly flat, slightly convex or even concave, with 
[ Palaeontology — Vol. ii.] 33 
