654 



THE WONDERS OF GEOLOGY. 



Lect. VI. 



Pentacrinites the ossicula composing the columns are 

 pentagonal, but in some species they have only four angles 

 (Lign. 145, fig. 10) ; and in some the angles are acute, in 



Lign. 149.- 



-Crinoidea from the Mountain limestone, 

 formations. 



and Silurian 



Fig. 1. Cyathocrinites piriformis, from the Wenlock limestone. {Sir It. I. Mar 

 chison' 8 Silurian System, PI. 17, fig. 6.) 

 2. Restored figure of Actinocrinites from the Mountain limestone. [Miller** 

 Crinoidea, p. 90.) a, the root-like processes of attachment ; b, the side- 

 arms ; c, the pelvis; d, the arms or tentacula. 



others rounded. The stems are furnished with numerous 

 side-arms (see the recent specimen, Lign. 144), and the 

 tentacula subdivide into innumerable branches, which ter- 

 minate in delicate articulated rays. Allusion has already 

 been made (p. 526) to the abundance and extreme beauty 



