Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/326

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322
STRUCTURE OF CRINOEDANS.


From the subjoined analysis of the component portions of the body of the E. Moniliformis, we see that it may be resolved into four series of plates each composed of five pieces, and bearing a distant analogy to those parts in the organization of superior animals from which they have been denominated. A similar system of plates, varying in number and holding the same place between the column and the arms of the animal, may be traced through each species of the family of Crinoïdeans. The details of all these specific variations are beautifully illustrated by Mr. Miller, to whose excellent work I must again refer those who are inclined to follow

closed, in Pl. 48. and Pl. 49, Fig. 1. and Pl. 50, Figs. 1, 2. In Mr. Miller's restoration of the Pear Encrinite (Pl. 47, Fig.1) they are represented as expanded. in search of food. These tentaculated fingers, when thus expanded, would form a delicate net, admirably adapted to detain Acalephans, and other minute molluscous animals that might be floating in the sea, and which probably formed part of the food of the Crinoïdea. In the centre of these arms was placed the mouth (Pl. 47, Fig. 1,) capable of elongation into a proboscis. Pl. 47. 6, x. 7, x. represent the bodies of Crinoïdea from which the arms have been removed.

In Pl. 50, Fig. 1 represents the superior portion of the animal, with its twenty fingers closed like the petals of a closed lily. Fig. 2 represents the same partially uncovered, with the tentacula still folded up. Fig. 3 is a side view of one of the fingers with its tentacula. Fig. 4 represents the interior of the body which, contained the viscera. Fig. 5 represents the exterior of the same body, and the surface by which the base articulates with the first joint of the vertebral column. Figs. 6, 7, 8, 9, represent a dissection of the four series of plates that compose the body, forming successively the scapulæ, upper and lower costa] plates, and pelvis of the animal. Fig. 10 is the upper extremity of the vertebral column. Fig 11 represents the upper surfaces of the five scapula, showing their articulations with the inferior surfaces of the first bones of the arms. Fig. 12 is the inferior surface of the same series of scapular plates, showing their articulations with the superior surfaces of the upper, or second series of costal plates, Fig. 13. Fig. 14 is the inferior surface of Fig. 13, and articulates with the first or lower series of costa] plates, Fig 15. Fig. 16 is the lower surface of Fig. 15, and articulates with the upper surface of the bones of the pelvis, Fig. 17. Fig. 18 is the inferior surface of the pelvis, Fig. 17, and articulates with the first or uppermost joint of the vertebral column, Fig. 10.