440 THE MEDALS OF CREATION. Cuap. XI. 
CHALK FORMATION. 
J.—SHANKLIN, OR LowER GREENSAND. Ly. p. 219. 
~_2 Etre ie ea 
Dr. Fitton’s Memoir, previously quoted, contains numerous figures — 
of the characteristic shells of this division of the Chalk, particularly — 
of the species which abound in the celebrated Whetstone of Devon- 
shire. Geol. Trans. New Series, vol. iv. Pl. XIJI—XVIII. See also © 
Prof. E. Forbes’s Catalogue of Lower Greensang Fossils, in the Quart. — 
Geol. Journal, vol. i. 
II.—Gatt anD Upper GREENSAND. Wond. p. 307; Ly. p. 218. 
Inoceramus concentricus; Wond. p. 330, fig. 1. 
sulcatus ;—fig. 3. 
Terebratula lyra; La fig. 219. 
Pecten quinque-costatus ;—fig. 203. 
Ostrea carinata ;—fig. 204. 
In Plates XI. and XII. of Dr. Fitton’s Memoir, there are figures of — 
more than twenty characteristic shells of this division of the Chalk. 
Ill.—Wuite CHatk. Ly. p. 211, Foss. South D., Geol. S. £. 
Some cretaceous species are delineated in Lign. 125, 126, 128, 129, 
130, 138; and Sir C. Lyell figures other species; but I must refer — 
the student to the Foss. South D., Geol. S. E., and Dixon’s Fossils of 
Sussex, as accessible works containing numerous figures of the fossil 
shells of the Chalk. Accurate descriptions and representations of 
all the British chalk shells, however, are still much required. 
Mr. Davidson has done much towards the illustration of our Creta- 
ceous Brachiopods; and the shells of the Cretaceous strata of the 
United States are figured and described in an elegant work by Dr. 
Morton, of Philadelphia. 
TERTIARY FORMATIONS. 
I.—Eoceng. Ly. p. 174; Wend. p. 226. 
IIl.—Miocenzg. Ly. p. 168. 
TII.—Puiocene. Ly. p. 161. 
The specimens figured by Sir C. Lyell have been so carefully s. 
lected, and are so well engraven, as to present a coup-d'eil of the 
most characteristic shells of the three grand divisions of the Tertiary 
Deposits. 
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