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REMARKS ON NEW SPECIES OF CRINOIDEA, 



The uppermost of these is the largest, expanded at five points around its margin, produc- 

 ing a pentangular piece. The extremity of the angular corners are greatly thickened up- 

 ward and downward, joined so that the two adjacent, large, thickened pieces completely 

 enclose and cover the thin pieces which lie between them at that point ; the smaller and 

 thinner pieces only appearing between the enlarged points of the thick pieces. In very 

 old (matured) specimens the thick and thin pieces are about ten — five of each class. In 

 this case the thick pieces have so increased in thickness as to entirely cover the thin pieces 

 lying between them. Sometimes cases arc seen when the thicker pieces have increased 

 to nine. When this is the case, one side of the column has the additional thickened 

 pieces on one side of it. The large pieces then are very thick, and arc implanted upon 

 the thin ones, covering, by their breadth, from four to six of them ; the thickened edges 

 of the large pieces forming five carina, along the length of the column, above the supple- 

 mental pieces. 



Below the smooth, rounded disks forming the column, they are alternately thick and 

 thinner. The thick pieces have bosses or enlargements upon them, from three to five each 

 piece, of the same model as those upon the thickened pieces at the upper extremity of the 

 column (not so large as they are, nor so prominent) ; between these bosses are from two to 

 six much less prominent — straight at the junction of the pieces with each other. The 

 large ones are most prominent in the centre of the thickness of the pieces upon which 

 they are placed. 



Between the thick and thinner pieces of this part of the column, are still thinner disks, 

 not seen in an unbroken column ; very distinct when the column is separated. This class 

 of disks is supposed to have been muscular, and not bony, or like the larger pieces be- 

 tween which they are placed. 



Resting upon the upper joint of the column — the largest piece in the column — arc 

 about nine thin disks or zones; the opening of the column, which passes through these, 

 being equal to half the diameter of the largest of these pieces; they diminish gradually 

 in circumference, rounding the pile to a hemispherical form; the upper zone by the open- 

 ing in the column, and its diminished size, is reduced to a ring about as wide as high. 

 The bottom piece of those composing the hemispherical {atlas) at the head of the column, 

 joins the upper piece of the column, the surface of both pieces being sharply cremdated 

 upon the joining surfaces. Surrounding the hemispherical pile of thin pieces at the head 

 of the column, are three (?) or five false basalar pieces. These pieces rise above the top of 

 the pieces of the atlas a distance equal to the thickness of two of the zone-pieces enclosed 

 by them; they terminate upward, in a thin knife-like edge, around the columnar opening; 

 their broad, external faces fitting into the columnar pit, partly sunk in the basal pieces, 

 and partly enclosed by and fitting the external surfaces of the inferior extremity of the 



