Organic Remains. 223 



I. The Column or Stalk. 



"The column usually consists of a long and slender cylindrical 

 stalk, composed of numerous short joints, so closely articulated 

 together, that, during- the life of the animal, it must have pos-essed 

 a very considerable amount of flexibility. It seems probable that in 

 species where the joints are alternately large and small, as in Glyp- 

 tocrinus, there was a greater degree of pliancy than in those instances 

 where it is formed of thin, equally large circular plates, asin the lower 

 part of the appendage in Rhodocrinus piriformis. In the Corni- 

 ferous limestone smooth round columns one inch in thickness are 

 often found, and these are so firmly constructed, that they must 

 have stood upright, supporting the body of the Orinoid, as upon the 

 top of a pillar. The columns are either pentagonal throughout 

 their whole length, or pentagonal in one part and round in an- 

 other, or altogether ro ind and smooth. In all the species they 

 are perforated from top to bottom by a small central canal, which 

 is also either circular or pentagonal. This canal no doubt served 

 the purpose of conveying the nourishment from the interior of 

 the body to every part of the column, by which its growth was 

 provided for. In nearly all Crinoids the lower extremity of the 

 column was attached to the bottom of the sea or some other solid 

 object, such as pieces of floating timber, either by a number of 

 branching rootlets, as in Rhodocrinus pyriformis, o: by a broad, 

 solid base, as in Cleiocrinus regius. I think however that eeitain 

 Lower Silurian species were free, and moved about through the water, 

 dragging their columns after them. I have seen at least a hundred 

 columns of Glyptocrinus ramulosus with the lower part preserved, 

 and could never discover any signs of an attachment. In this 

 species the column at the upper end is often half an inch in thick- 

 ness, and it tapers gradually to half a line at the lower extremity, 

 a shoit piece of which, when found perfect, is always closely curled 

 up, like a miniature coil of rope. I think also that sometimes the 

 attached species had their columns broken oft* by some accident, 

 and that the animal lived long afterwards free, but with a portion 

 still connected with the body. 1 have seen specimens of Rho 

 docrinus pyriformis with from six to ten inches of the column at- 

 tached to the base of the cup, with the terminal joint where the 

 fracture occurred rounded, and the alimentary canal closed, or, as 

 it were, healed up. There does not appear to be any way of ac- 

 counting for this condition of the column, unless upon the above 

 supposition. 



