101 



them as closely allied to, if not actually belonging to this 

 family. 



The pentacrinm appears to have been an animal with a 

 pentagonal, articulated, vertebral column, from the superior 

 part of which, from five bases, proceeded as many articulated 

 arms, dividing into ramifications, closely beset with jointed 

 fingers, bearing much of a plumose appearance. 



The form and structure of the fossil remains of the dif- 

 ferent species of this genus, plainly show that the animal 

 possessed similar powers of seizing the surrounding objects 

 of its prey, as the encrinus, but on a wider range. 



The fossil vertebrae of this genus are small, flat, and 

 generally pentagonal, stelliform stones, ornamented -on both 

 their upper and under surfaces with five petal-formed 

 figures, from the supposed resemblance of which to five 

 lilies the name of the genus, pentacrinus, has been derived : 

 these form, by their union, asterice columnares, or columnar 

 star-stones, being parts of the pentagonal spine ; in the 

 figure of which, as well as in the forms of the markings 

 of the vertebrae, considerable differences occur in dif- 

 ferent species. 



On the upper extremity of the spine are disposed the 

 parts which form a pelvis, being in all probability the ven- 

 tricular cavity, and those parts also which give support to 

 the limbs. As the use of these parts is more obvious in this 

 genus than in that of the encrinus, an excuse will be more 

 readily admitted for adopting for them those terms which 

 are applied to the supposed corresponding parts in the more 

 perfect animals. 



On each of the five sides of the upper end of the spine, 

 PI. ix. fig. 16, three pieces are disposed, the largest of 

 which (a) performs the office of scapula, its upper coty- 

 loidal surface receiving the first bone of the arm (c) : on 

 this is placed the second bone (d)^ the upper part of which 

 is divided into two obliquely disposed surfaces, on which the 



