EXPLANATION OF THE PLATES AND WOODCUTS. 



PLATE XX. 



Illustrates Mr. Owen's memoir on some of the soft parts of the Hind- Fin of the Ichthyosaurus, 

 indicating the shape of the fin when recent: p. 199. 



PLATE XXL 



Illustrates Mr. Owen's paper on the Hyracotherium leporinum (p. 203-206) and lAthornis 

 vulturinus (p. 206-208). For descriptions of the figures, see pp. 206 and 208. 



PLATE XXIL 



Illustrates Mr. Owen's account of some Ophidiolites [Palteophis toliapicus) from the London 



Clay : p. 209. 

 Fig. 1. A group of vertebrae and ribs of the Palaophis toliapicus, from the London Clay, 



Sheppey : in the Hunterian Museum. 

 Fig. 2. A chain of vertebrae thirteen inches and a half in length, of the same species, from 



the same formation and locality: in the museum of Mr. Bowerbank. 

 Fig. 3. A group of six vertebrae, of the same species, from the same formation and locality: 



in the museum of Mr. Bowerbank, 

 Fig. 4. Side-view of a vertebra of the Palaophis toliapicus. 

 Fig. 4a. Side-view of a corresponding vertebra of the Python tigris, from a specimen nine feet 



in length. 

 Fig. 5. Anterior view of a vertebra of the Paleeophis toliapicus. 

 Fig. 5a. Anterior view of a corresponding vertebra of the Python tigris. 

 Fig. 6. Under view of the vertebra of the Paleeophis toliapicus. 

 The same letters indicate the same parts in each figure. 



a. The concave anterior articular surface of the body of the vertebra. 



b. The convex posterior articular surface. 



c. The articular tubercle for the head of the rib. 



d. The anterior articular surfaces of the oblique and transverse processes forming the 

 ' tenon' joint, in which the ' mortise' e at the posterior part of the neurapophysis is 

 infixed. 



e. The spinous process. 



All the figures are of the natural size. 



WOODCUTS 



To illustrate Mr. Buddie's paper on the Great Fault, called the Horse, in the Forest of Dean : 



p. 215. 

 Section of the drift through the Horse Fault and of the beds on each side of it: p. 216. 

 Plan of the Horse Fault and of the irregularities in the surface of the coal-seam on each side 



of the Fault: p. 217. 



