STRUCTURE AND MODE OF GROWTH. 181 



its apex to a few pellucid tentacula : no other part of 

 the solid fabric is as yet observable. In specimens 

 that have made a little more progress, together with 

 the elongation of the pedicle or stem, its joints begin 

 to make their appearance ; the body acquires a larger 

 size and brownish tint from a grosser food ; the ten- 

 tacula of the mouth protrude in a greater degree, and 

 move slowly in various directions. In others still 

 more advanced, the joints of the stem become quite 

 obvious from their opacity and white colour, and the 

 base of the future arms, as well as the auxiliary side 

 arms, are rendered palpable. The arms from this 

 period lengthen apace from their bifurcation, arid 

 have superadded to them a double range of trans- 

 parent jointed tentacula ; so that the animal begins to 

 put on a more perfect appearance, and now for some 

 time merely acquires a somewhat greater size and an 

 extension of its arms, which, although they solidify 

 from their origin upwards, remain pellucid and thick 

 at their apices, where elongation, evolution, and the 

 secretion of calcareous matter are gradually going on. 

 Here, then, we have the form, the structure, and the 

 mode of growth of the Encrinite exemplified before 



us, and can see with our own eves what, until the 



> 



discovery of this little animal doubtless common 

 enough on our own coast remained involved in im- 

 penetrable mystery, viz. the nature, habits and attri- 

 butes of the millions of extinct Crinoideans whose 

 remains constitute our limestone cliffs and encrinitic 

 marbles. 



But the interest which attaches itself to the grow- 



