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ON COLLECTING FOSSIL ECHINODERMATA. 354 
is unnecessary to offer any suggestions for their development ; 
_ of course they must not be removed from the stone. 
Among the detached ossicula dispersed through the chalk, 
the student will remember that the large madrepore-like 
tubercle of the Star-fishes, (ante, p. 304,) may often occur, 
It may easily be mistaken for an encrinital body, or for a 
coral, but an accurate inspection will show that it is not 
composed of anchylosed plates, like the receptacle of an 
Apiocrinite, but has surfaces for attachment to other ossi- 
cula; while the ends, which in a crinoideal column would 
have radiated surfaces, are rounded and entire. 
In collecting Echinites, much caution is required in dis- 
secting specimens surrounded by spines. If imbedded in 
hard limestone, or in laminated clay, it is scarcely possible 
to preserve the spines in connexion with the shell; but it 
often happens that the Cidarites of the Oolite are attached 
by the base to the solid limestone, and the case with the 
Spines is imbedded in sandy, friable aggregate, not difficult 
of removal. A specimen in my cabinet, with upwards of 
fifty spines attached to the shell, was obtained under such 
circumstances.* 
The Chalk Echinites will be found to possess spines more 
frequently than is commonly supposed, if care be taken to 
explore the surrounding chalk before it be removed. I have 
often procured Cidarites with spines, when there were no 
apparent vestiges of these appendages, by carefully scraping 
away the surrounding mass until the extremity of a spine 
appeared, and then tracing it up to its connexion with the 
shell; another point was discovered by further removal, and 
that was developed in the same manner; and at lengtha 
Cidaris with several spines was obtained. The chalk around 
the mouth should always be cautiously removed in the den- 
tated species, in the hope of preserving the teeth, as in the 
specimens, Lign. 101, fig. 1, and Lign. 104, fig. 1. 
* Now in the British Museum. 
