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In those Crinoidea where the costals are wanting, action is continued over 
interposed intercostal plates or the enlarged scapule, where as in Platy- 
crinites these are made subservient to the use of costal plates. Where the regu- 
lar number of costal plates exists, and intercostal, interscapulary, or pectoral 
plates occur, as in Actinocrinites and Rhodocrinites, these can only be consi- 
dered as analogous (yet infinitely more conspicuous and developed) to those 
plates that cover the integument between the second costal and scapule of the 
pentacrinite. 
x 
In the Crinoidea, generally the articulation of the arms is to the scapule 
resting on the costals, which are inserted on the pelvis, whose joints adhere 
to the column, and enclose a small perforation in the centre that leads to the 
alimentary canal. 
The alimentary canal is only a continuation of the stomach, (a sort of 
coecum ?) carrying nourishment to the further end of the column, and as it 
proceeds, distributing it to the auxiliary side arms, by means of minute vessels 
under the epidermis. 
An integument protected by numerous minute plates extends over the 
abdominal cavity, the channel in the arms, fingers, and tentacula, furnishing » 
protection to the viscera and vessels extending under it. 
It is this plated integument, where spreading over the abdominal cavity, 
which has in its centre the mouth of the animal, apparently formed for suction 
and gorging, and hence its surrounding muscle is able to protrude it under the 
form of an elongated proboscis. 
Numerous tentaculated fingers surround the mouth, and hence prove by 
the closeness of the apparatus so provided, that the food detained by them 
must be very small. 
A mouth capable of being elongated into a proboscis, and fingers con- 
structed fur detention, indicate that the animal watched for its prey, and took 
it in from above. 
A perforation extending through the centre of the arm, finger, and tentacular 
Joints, indicates the passage of a nourishing vessel, analogous to those extend- 
