ENCRINITES. 1 17 



of the shale-blocks he is working upon. These are 

 verily written " within and without ; " and the iron 

 sulphite into which nearly all the organic remains of 

 these beds have been converted, makes them look as 

 if they had been electrotyped on the surfaces of the 

 black shales. 



At Bradford, near Bath, we have numerous 

 Encrinites occurring in clayey rocks instead of in 

 limestone, their usual storehouse. This clay (sixty 

 feet thick) is in the Oolitic formation, and proves 



Fig. 93. — Head of Ichthyocrinns, an Fig. 94, — Head oi Encaly/>tocrinns, a 

 American Silurian genus of Crinoids. Devonian Encrinite. 



exactly the same conclusion we have drawn from the 

 Encrinites buried in the Primary rocks, namely, that 

 muddy sediments always kill them off and bury them 

 where they are. In the hard slates (formerly shales) 

 of the Upper Silurian formation, about a couple of 

 miles from Llangollen, in North Wales, the student 

 may find some beautiful specimens of the character- 

 istic Upper Silurian Encrinite known as Actifwcrinjis 

 pnlcher. Well does it deserve its specific name, for no 

 Encrinite exceeds it in gracefulness of shape. At the 



