mens, in my own possession, as seem to determine the relationship 

 between the particular species of spines and of echinal shells. 



The ACICUL^E capitata, in their respective varieties of forms and 

 colours, are found chiefly belonging to the echini of the genus miUaris 

 and variolata. 



Instances of their preservation, in a petrified state, have not been fre- 

 quently mentioned. Two unconnected specimens are figured by Volk- 

 mann, Siles. Subt. Tab. xxx. Fig. 17, 18 ; and it is this species of which 

 Gesner speaks, de Petrificat. p. 36 d. as aculei, s. radioli leves, exquisite 

 cuspidati. Two specimens are also figured by Miiller, Delic. Natur. Tab. 

 p. i. Fig. 1, 5. But no instances are given, in any author, of their 

 preservation in a fossil state, in connection with their shell. In the spe- 

 cimen in chalk, Plate I. Fig. 10, one of these spines, ofasubulated form 

 and striated surface, is seen in that situation, which gives full reason to 

 suppose its relationship to the shell which it accompanies. The flint speci- 

 men, Plate III. Fig. 1, is interesting, from its showing that E. saxatilis 

 is provided with spines of a similar shape : in one part the spines are 

 seen, with their articulating terminations, lying close to the points to 

 which they belonged ; and in another, one of the spines is seen in the 

 substance of the flint, still attached to the shell. In the remarkably fine 

 specimen from Stunsfield, in Oxfordshire, Tab. I. Fig. 8, some little 

 variation is observable with respect to the spines. Like the former, they 

 are striated, subulated, and rather bent ; but they gradually, though very 

 slightly, swell a little about their middle, and thence become somewhat 

 fusiform. 



In the flint fossil, Plate I. Fig. 5, which was considered as one of the 

 most valuable in the Leverian Museum, spines of this class are still seen 

 adherent to the echinital crust, and imbedded and passing into the solid 

 flint. These are subulated like the preceding, but are more straight. 

 The echinite of this specimen appears to be of the variolated kind. 



In the interesting specimen of Cidaris papillata, from Calne, Plate IV. 



