430 THE MEDALS OF CREATION. Cuap. XI. 
the innermost cells. We shall again have occasion to refer 
to this interesting fact, when investigating the chambered 
cells of the Cephalopoda. It may be necessary to remark, 
that it does not appear that the vacant interspaces in the 
Euomphalus served the special purpose of the air-chambers 
of the Nautilus and Ammonite. 
Murcuisonta. Zign. 137. An elongated spiral shell, 
having the outer lip deeply notched, as in the Pleuroto- 
maria (a, Lign. 137). There are upwards 
of 50 species of this genus, which are cha- 
racteristic of the paleeozoic rocks. They 
occur in the Permian, Devonian, and Lower 
Silurian deposits ; the specimen figured is 
from the Devonian, or Old Red of the 
Eifel. 
Curton. Valves of Chitons have been 
found in the Magnesian limestone, near 
Sunderland, by Prof. King, (Permian Fossils, 
ren. 137. 
Murcutsoxtra Pal. Soc. p. 202, pl. xvi.), and in the Silu- 
ANGULATA. 
rian rocks of Ireland, by Mr. Salter, Geol. 
Devonian ; Eifel. oe 
Journal, vol. i. p. 48. 
SPHARULITES.* Lign. 138.—No vestiges of a shell of 
this genus had been noticed in the English strata, until 
my discovery of some fragments in the Lewes Chalk 
in 1820; from the lamellated structure of these fossils, 
I mistook them for corals, until specimens were obtained 
sufficiently perfect to show the form of the originals; 
these were described in the Geol. 8S. H. (p. 130), under 
the name of Hippurites. But these fossils are more 
nearly related to the Spherulites, which differ from the 
* This genus has been referred by some conchologists to the 
Bivalves, and by others to the Univalves. 
