ATTACHMENT TO EXTRANEOUS BODIES. 329 



those of the Pear Encrinite, by which this Pentacrinite could 

 have been fixed permanently to the bottom, and the farther 

 fact of its being frequently found in contact with masses of 

 drifted wood converted into jet (PI. 52, Fig. 3.,) leads us to 

 infer that the Briarean Pentacrinite was a locomotive ani- 

 mal, having the power of attaching itself temporarily either 

 to extraneous floating bodies, or to rocks at the bottom of 

 the sea, either by its side-arms, or by a moveable articulated 

 small root.*' 



the action of contractile muscular fibres on the internal surfaces of each ver- 

 tebra. 



* The specimens of Briarean Pentacrinite at PI. 52, Fig, 3. from the 

 Lias at Lyme Regis, adheres laterally to a portion of imperfect jet, which 

 forms part of a thin bed of Lignite, in the Lias marl, between Lyme and 

 Charmouth. 



Tliroughout nearly its whole extent, IVIiss Anning has constantly observed 

 in this Lignite tlie following curious appearances: The lower surface only 

 is covered by a stratum, entirely composed of Pentacrinites, and varying 

 from one to three inches in tliiclincss ; they lie nearly in a horizontal posi- 

 tion, with the foot-staiks uppermost, next to the lignite. The greater num- 

 ber of these Pentacrinites are preserved in such high perfection, that they 

 must have been buried in the clay that now invests them before decomposi- 

 tion of their bodies had taken place. It is not uncommon to find large slabs 

 several feet long, whose lower surface only presents the arms and fingers of 

 these fossil animals, expanded like plants in a Hortus Siccus; whilst the 

 vppcr surface exhibits only a congeries of stems in contact with the under 

 surface of the lignite. The greater number of these stems are usually pa- 

 rallel to one another, as if drifted in the same direction by the current in 

 wiiich they last floated. 



The mode in which these animal remains are thus collected immediately 

 beneath the Lignite, and never on its upper surface, seems to show that the 

 creatures had attached themselves, in large groups, (like modern barnacles,) 

 to the masses of floating wood, which, together with them, were suddenly 

 buried in the mud, wliose accumulation gave origin to the marl, wherein 

 this curious compound stratum of animal and vegetable remains is imbedded. 

 Fragments of petrified wood occur also in the Lias, having large groups of 

 Mytili, iti the position that is usually assumed by recent mytili, attached to 

 floating wood, 



28* 



