EXPLANATION OF PLATE 47. 
81 
Fig. 6. Body of Apiocrinite.s 30-dactylus (Nave Encrinite 
of Parkinson) copied from Miller’s Crinoidea, P. 98. 
PI. 11. (See V. 1. p. 429. Note.) 
Q. Pectoral Plates. 
R. Capital Plates. 
X. Orifice of the Mouth, or Proboscis, capable of elon- 
gation for sucking in food. 
Fig. 7. Another Body of a Nave Encrinite, drawn by Mr. 
J. Sowerby from a specimen in the British Museum. 
The same is Figured by Parkinson, in his Organic 
Remains Vol. II. PI. XVII. Fig. 3. The lateral pro- 
jections are the commencement of the side arms. 
This specimen has been corroded with acid, and con- 
sequently has lost the superficial Corrugations and 
in his admirable Monograph on Crinoidea, p. 97. “ The mechanism 
of the joints of the side arms, wliere these insert into the column, is 
well worthy of notice, particularly in old specimens. In the earlier 
stage of their formation, the side arms being very short, and having 
then little weight, a less firm mode of adhesion to the column than 
becomes requisite at a subsequent period, being then sufiicient, we 
do not find more than one joint lodged in a socket, or concave im- 
pression on the column ; but when increase of size renders a stronger 
support necessary, two or three succeeding joints of the side arms 
become imbedded in this socket, (for which its extension as already 
noticed allows room) and these joints instead of being arranged in a 
series branching otf at right angles from the column, become oblique, 
their direction inclining upwards, so as to aid in bearing the addi- 
tional weight. The first joint of the side arms, where thus obliquely 
inserted in the columnar socket, have that portion of their circum- 
ference w'hich is presented towards the upper part of the column, 
truncated, in such a curve as may fit them to the concavity of the 
impression where they rest against it. 
The surface of these joints, which fit into the columnar impression, 
is smooth, being destined for adhesion only, but the articulating sur- 
face beWveen the contiguous joints, wliere motion also is to be allowed, 
exhibits the usual mechaaism of radiateil ridges and furrows. These 
joints are convex on the side nearest the column, and concave on that 
Most remote.” 
G. IT. 
G 
