as not, I believe, to show its original surface; and hence it is impos- 

 sible to determine at present any thing respecting the substance with 

 which it was connected at this part, or the kind of articulation which 

 was here employed. It however very nearly resembles the smaller 

 modiolus, from Ireland, which is represented in Plate XVII. 



Among the enigmas which must be left to be solved by the indus- 

 try of future inquirers, into the original nature of the various species 

 of encrinites, there is no one which appears to me to be more difficult 

 than the determining the original properties and mode of existence 

 of the animal, of which a part of its vertebral remains, m the state of 

 lime-stone, is represented Plate XVI. Fig. 16. Two remarkable cir- 

 cumstances in this fossil must attract your admiration, and, of course, 

 excite your curiosity: the contorted forms in which the vertebralco- 

 lumn is disposed, and the remarkable processes, which appear to 

 have issued from the sides of the vertebrae-. 



The first inquiry which naturally arises, on viewing the parts of 

 an animal disposed in a form entirely different from that which 

 any other species of that kind of animal assumes, is, whether or 

 no that position is the effect of accident? To this question I ac^ 

 knowledge, tha% on the first view of this specimen, I was much in- 

 clined to anticipate an affirmative answer. A careful examination 

 into the structure of these fossil remains soon, however, convinced me 

 that these contortions were natural to this part of the animal, and 

 that the construction here adopted, displayed the most admirable in- 

 stance of the wise adaptation of means to the accomplishment of a 

 proposed end, In the examination of most of the preceding species 

 of encrinites, we discovered that, for the purpose of securing a 

 greater degree of freedom of motion, in that part of the vertebral co- 

 lumn which- was nearest to the superior extremity of the animal, a 

 peculiar structure was employed - the vertebrae were alternately 

 wider and narrower, and the narrower were received into the perpendi- 

 cularly lengthened margin of the wider; the outer crenulated edge of 



