” 
240 THE MEDALS OF CREATION. Cuap. VII. 
under consideration entirely differ from their supposed homo- — 
logues ; their original substance not being siliceous, but — 
flexible and membranous ; and that instead of being spores 
of alge, they are probably the gemmules either of porifera, 
or of polypifera. 
To avoid the perpetuation of the error by the retention 
of the botanical name of a recent genus of plants, for 
fossils whose vegetable origin is very problematical, and 
which are entirely distinct from their supposed analogues, 
T would substitute that of SpPrniFERITEs,* a term simply 
expressive of the general aspect of these bodies; that of a 
globe or sphere beset with spines. The appearance of these 
fossils will be understood by the examination of a group 
discovered by Mr. Reginald Neville Mantell, in a fragment 
chipped off from a flint pebble; and I will describe the mode 
by which these minute objects were detected, as it offers a— 
good practical lesson for the young investigator. 
The chip of flint is represented, of the natural size, in 
Lrgn. 77, fig. 1; it was immersed in oil of turpentine for a 
short time, and then placed on a piece of glass, and examined 
with a moderate power, by transmitted light, the turpentine 
having rendered the translucent flint almost as transparent 
as glass; this appearance is shown in jig. 2; the organisms — 
here represented are from 53, to =, of an inch in diameter. 
The half-inch object-glass was next employed, and jig. 3 
gives the result. The quarter-inch object-glass, and a cor-— 
responding eye-piece, were then substituted, and by the 
adaptation of a camera lucida, jigs. 4, 5, and 6, were de- 
lineated. As jig. 5 proved to be a new species, it was named 
after its discoverer. 
The specimens in flint, when rendered transparent and 
viewed by transmitted light under a high power, as shown 
in Lign. 78, and 79, appear as hollow globular bodies, beset 
* From spina, a spine, and fero, to bear. — 
