260 THE MEDALS OF CREATION. Cuap. VII. 
nected by transverse tubular processes ; the cells are deep and 
radiated by numerous lamelle. 
The external aspect of these fossils is that of a cluster of 
cylindrical pipes, more or less parallel, connected by short 
transverse branches. They are the Zubiporites of Mr. Park- 
inson, who has given admirable figures of several specimens. * 
In these fossil corals that excellent observer first detected 
the animal membrane. A slab of marble, whose markings 
are produced by the section of the inclosed tubes of a Syrin- 
gopora, is represented, Wond. p. 644, fig. 2. The Mountain 
limestones of Derbyshire, and of Clifton, on the banks of the 
Avon, contain figured marbles of this kind, which are manu- 
factured into vases, tables, &c. The genus is extinct. 
Lirnosrrotion Cotumnaria (Wond. p. 641, jig. 8).— 
Polyparium massive, solid, composed of ageregated, con- 
tiguous, parallel, prismatic tubes, each terminated by a star: 
cells shallow, multi-radiate, stelliform. 
Species of this extinct genus are common in the mountain 
limestone, in large masses, which, from the pentagonal form, 
and parallel arrangement of the tubes, appear like clusters 
of miniature basaltic columns.t 
Cyatnopnyiium. Lign. 87, figs. 1, 2. (Wond. p. 641, 
figs. 1, 3.)—Polyparium turbinated, simple or compound, 
internal structure transversely chambered or lamellated; 
cells polygonal, radiated, depressed in the centre. 
The corals of this genus are so abundant in the Silurian 
rocks, that the seas of that epoch must have swarmed with 
them. The simple turbinated forms are often several inches 
long, and being somewhat curved, have obtained the popular 
name of “ petrified rams’-horns.” 
Upon slitting one of these corals vertically, as in Lign. 87, 
fig. 1, the axis of the polyparium, beneath the cell, is found 
* Pict, Atlas, pl. xxv. fig. 1. Syringopora geniculata, Pict. Atlas, 
pl. xxxiv. 
+ Lithostrotion striatum, Pict. Atlas, pl. xxxvii. figs. 5, 6. 
