312 Professor Sedgwick and Mr. Murchison on the 



"■2. Thick-bedded, brown-coloured, coarse limestone. 



3. Cream-coloured, compact, argillaceous limestone, with a conchoidal frac- 

 ture, very much resembling the white lias of Somersetshire, and containing 

 true Ammonites of a large species, one of which approaches Ammoniles 



biplex. 



4. Dark, thinly foliated, calcareous shale, with occasional bands of marl- 

 stone. 



5. Dark, marly shale, with small nodules of dark blue, argillaceous limestone, 

 in the centres of which are frequently Ammonites and other organic bodies. 

 These concretions are undistinguishable from the cement stones of the lias 

 shale of Whitby. The higher beds of shale are separated by stony beds of 

 dark-coloured, bluish limestone, and in a cliff near the Waterfall are not less 

 than 300 feet in height. Among the fossils we collected are the following. 



Anmionites Conybeari, or a variety of it, identical with an Ammonite of 

 the lias of Wirtemberg. 



a new species. 



Mya ? 



Pecten, very near Pectcn dentatus and three other undescribed species. 



Perna, of more than one species. 



Terebratula, near T. hastata of the mountain limestone. 



Ostrea. 



Small Gryphaea ? 



Other indescribable minute spiral shells. 



Caryophyllia (?), &c. &c. 



in the preceding section we find that the dark bluish shales and limestones 

 pass, in descending order, into strata of greenish marl with bubordinate stone 

 bands, which we consider as the upper portion of the new red sandstone. 

 None of the shells in the overlying limestone bands belong to the peculiar suite 

 of the mnschelkalk. One elongated bivalve, indeed, somewhat resembles the 

 Mijtilus soclalis of Schlotheim ; but all the specimens of chambered shells are 

 true Ammonites, and admit of no comparison with the peculiarly chambered 

 shells {Ammonites nodosns, &^c.) of the mnschelkalk. Prom the mineral 

 character of the upper group of blue shale and limestone, as well as from its 

 position above the red sandstone, and from its group of fossils, we venture to 

 place it on the parallel of the lias. 



it may be objected to the preceding classification, that it is founded on 

 imperfect zoological evidence, inasmuch as, perhaps, none of the fossils enu- 

 merated can be strictly identified with species found in the lias formation of 

 this country : but the same argument would apply with almost equal force to 



