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and nearly form a segment of a circle : their internal edges, which 
are also somewhat circular, are finely crenulated. Their inferior sur- 
faces, (c, 1) have a few ridges and depressions, by which they are fit- 
ted for articulation with the superior surfaces of the bodies (ribs) de- 
scribed in the last paragraph : but their superior surfaces (2) are tolera- 
bly smooth, having only a little rising on each, by which they are fitted 
for articulation with the inferior surfaces of the next series of bodies. 
These, (d) in their general form, bear some resemblance to the 
former bodies, but are considerably thicker on their outer than on 
their inner edges. Their inferior surfaces (d, 1) are a little hollowed out, 
by which they are adapted to the superior articulating surfaces of the 
former bodies (clavicles) : but their superior surfaces (2) rise gra- 
dually in the centre of their outer mai’gins, so as to render their outer 
surfaces of a triangular form, and to separate their upper into two 
obliquely disposed surfaces. These oblique superior surfaces are 
the parts adapted for articulation with the inferior surfaces of the 
next series. Rosinus unites these with the preceding pieces, and 
names them, when thus united, Radices radiorum. With these bodies, 
and which I have therefore termed scapula;, are articulated the 
ARMS of the animal (e;) one proceeding from each of the ob- 
lique surfaces of these bodies, and are therefore ten in number. In 
the specimens which were seen by Rosinus, these arms were formed by 
seven pieces ; but from the examination of those which I possess, I 
find a considerable difference in this respect : in one instance there 
are seven ; in another, four ; and in others, six of these pieces. The 
first of these, that which immediately articulates with the scapula, 
is thicker than the rest, and is of an irregular form, much better to 
be comprehended from its representation, than from any description. 
To this is adapted a thinner, but somewhat similarly shaped piece; 
on which, in succession, are disposed other thinner pieces, with which 
the arm is completed. At (f) is represented the two first ossiculse of 
the arm united together. 
