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part is, in this species, formed of three trigonal pieces, the two 

 lowermost of which are very thin, and are applied by one of their 

 sides to the vertebrae ; but the uppermost suddenly widens, so that 

 the upper part of the surface, which is applied to the vertebral co- 

 lumn, is exactly of the width of the vertebrae themselves*. On the 

 summit of this body is a semilunar cavity, sloping outwards and 

 downwards, in which a central foramen and a transverse ridge is ob- 

 servable. Between each of these scapulae, on each of the angles of 

 the vertebral column, a small body, 6, is placed, which, from its 

 assisting in attaching the scapula to the column, I consider, as I 

 have done in the encrinites, as performing the office of a clavicle. 

 The whole of these bones form the pelvis, in which the visceral part 

 of the animal was, in all probability, deposited. 



Immediately on the semilunar cavity of each scapula is disposed the 

 piece which forms the first joint of the arm of the animal, Plate 

 XVII. Fig. 15, c; and on this is placed the second piece, d, the lower 

 side forming the surface with which it articulates with the preceding 

 piece, and the two upper sides forming the surfaces with which the 

 two first pieces of a new series of ossiculae are articulated. At Fig. 13, 

 is represented one of these ossiculoe of its natural size, with its sur- 

 face of articulation : and beneath it is a representation of the same 

 body slightly magnified. 



The first ramification of the arms may be said to be completely dicho- 

 tomous; but of the subsequent innumerable ramifications, a correct idea 

 can only be obtained by a view of this part of the animal, or its repre- 

 sentation, which has been endeavoured to be faithfully given, Plate 

 XVII. Fig. 9, and Plate XVIII. Fig. 1. Another view of these parts 

 is given, Plate XVIII. Fig. 2, where the ossiculoe are denoted by 

 the same letters as in Plate XVII. Fig. 15. The specimen, Plate X VIII. 



* Were it not that it might have the appearance of aiming at too great a degree of 

 nicety, and of labouring too much to make out the supposed analogy, 1 should have 

 named the two lowermost of these bodies ribs, from the circumstance of their connection 

 with the vertebrae and the scapulae, and for the sake of preserving a greater degree of uni- 

 formity in the nomenclature. 



