320 THE MEDALS OF CREATION. Cuar. IX. 
Fuint Casts or Turpan Ecurnites. Lign. 103.—The 
siliceous casts of the shells of the Turban Echinites are inter- 
esting objects, for they are often beautiful models of the 
interior. A specimen of this kind is represented in Lign. 
101, fg. 5. Casts of the larger Cidarites are often seen on — 
the ploughed lands of the South Downs, in beds of gravel, — 
and among the shingle on the sea-shore of chalk districts; _ 
appearing as flattened spherical bodies, with a circular pro- — 
tuberance at each pole, and vertical rows of nodular pro- — 
jections. Impressions of the external surface of the cases — 
are also frequent on chalk flints, and exhibit exquisite casts, 
in intaglio, of the mamillated tubercles, and ambulacral 
grooves and pores. 
Lien. 163. EcuiniTaAL REMAINS 1N Fuint. Chalk. Lewes. 
(One-third the natural size.) 
Fig. 1.—Cast of an ANANCHYTE, showing the form of the plates. 
2.—Im print of a segment of a CIDARITE on a pebble. 
a.—One of the impressions of a spinous tubercle: nat. 
3.—Portion of an ANANCHYTE, having the cavity of the shell 
covered at the bottom with flint, and lined above with 
crystals of carbonate of lime. 
A fragment of a flint, impressed by a portion of a Cidarite, 
is represented Lign. 103, fig. 2. The perforations around 
