108 THE MEDALS OF CREATION. Cuap. VI. 
to the cast, and consequently the surface of the latter is 
generally jointed and ribbed. 
The true external surface of the cortical investment is 
marked with longitudinal striz, without any indications 
of joints or constrictions ; but the position of the original 
articulations is indicated in some specimens by the presence 
of small verticillate scars, to which leaves were appended,* as 
in the example figured by M. Brongniart, of which Lagn. 14, 
fig. 1, is a reduced figure. 
ill 
| 
Lien. 15. CALAMITES, IN CoAL SHALE. 
Vig. 1.—CALAMITES RADIATUS, with the remains of one of the sheaths.—} nat, 
2.—Stem, with remains of roots.—+ nat. 
3.—CALAMITES APPROXIMATUS, showing the curved Jower end of the 
plant.t—+ nat. 
The stellate appearance on the upper part of the stem 
figured in Lign. 15, jig. 1, is produced by the zone of leaves 
* See Mr. Dawes, “ On the Structure of Calamites,” Proc. Geol. Soc. 
1851, vol. vii. p. 197. 
+ This specimen has been inadvertently drawn with the base 
uppermost, 
¥ 
