Stone Lilies af the Trenton Limestone. 56 



^f the secondary rays. The pelvic plates are small and barely visible, being 

 in part concealed beneath the basal plates of the rays. They have a pro- 

 jection at their bases, which forms a ring all round under the base of the 

 ■cuja. In some of the specimens this ring is sharp and overhangs, as it 

 were, the top of the column. In other specimens it is thicker and rounded. 

 The free rays or arms are, at first, twenty ; two springing from the 

 top of each secondary ray. At the height of about three fourths of an inch, 

 in specimens of the size of those above figure'l, they again divide, a few of 

 ■them, however, (the precise number not ascertained) continuing single to 

 their extremities. They are fringed on their inside with two rows of tenta- 

 <jula, from two-eighths to five-eighths of an inch in length. The arms are 

 composed of two series of ossicula, which interlock with each other, as 

 *hewn in Fig., 7 where a side view of a portion of an arm, with its tentacula 

 ^attached is given. On the back of one of the arms, at its base, eight joints 

 were counted in the length of one eighth of an inch, but higher up they are 

 more numerous. It has not yet been ascertained with certainty whether the 

 ientacula were jointed or not- Each appears to have four or five joints. 



.1 



Figs. 4 5 6 7 8 



Fig 4. — Is a very accurate drawing- of a portion of the column 

 immediately next to the base of the cup. 



Fig 5. — Is a portion of the column several inches below the base 

 of the cup. 



Fig 6. — Shews the crenulated thin plates of the c<^lmnn betiveen 

 the thicker ones. 



Fig 7. — A side view of a portion of one of the arms.. 



Fig 8. — A section across one of the arms ; the two long processes 

 below are tentacula. The straight line across the 

 base of the small half circle at the top of this figure 

 should be arched upwards to shew the groove in the 

 arm. 



The column is round and annulated, the projecting rings being very 

 •close to each other, and most of them thin and sharp at the Ijase of the cup 

 -and for a short distance below. They are farther apart and their edges are 

 thicker and rounded, or slightly notched in the remainder of the column. — 

 At the distance of ten inches from the base of the cup, and thence down- 

 ward, there are from 16 to 20 amiulations in an inch on an average in several 

 specimens. Between the annulatioos, the column is composed of thin plates 

 with crenulated edges, the ancrles fittiuo- into each other, as seen in the en- 

 larged figure 6 above. There are from five to ten of those thin plates be- 



