OF CREATION. 



93 



number of fine tubular or hair-like appendages are, in 

 many cases, attached to it, sometimes passing through 

 the fibrous shell, but at other times only extending 

 from the line of junction of the two valves, which are 

 not connected by any hinge, and which were pro- 



Fig. 33 Fig. 34 



SPIRIFER. 



PRODUCTUS. 



bably at once united and fastened to some solid body 

 by this contrivance. As in the other brachiopods, 

 there appears here also to have been a mechanical 

 contrivance for keeping the valves partly asunder; 

 and it would seem, that, at least in some species, the 

 shell was very thin, and readily adapted itself to the 

 shape of the stone on which the animal had fastened 

 itself. The fossil shells of the productus are ex- 

 tremely abundant throughout the carboniferous lime- 

 stone, and are found in a limestone overlying the 

 coal-measures ; but they are rarely found in the 

 millstone grit or the coal-measures themselves, the 

 circumstances of the deposit being probably unfa- 

 vourable for the existence of such animals. 



The singular spire of the Spirifer (fig. 33), often 

 well preserved and generally occupying a consider- 

 able portion of the interior of the shell, is character- 

 istic of the genus, and alluded to in its name. The 



