26 EXPLANATION OF PLATE 14. 



Lyme Regis, presented to the Oxford Museum by Viscount 

 Cole, enclosing within its ribs scales, and digested bones of 

 Fishes, in the state of Coprolite. This coprolitic mass seems 

 nearly to retain the form of the stomach of the animal, c, 

 Coracoid bone, d, Scapula, e, Humerus, f, Radius, g, Ulna. 

 (Scharf. Original.) 



Plate 14. V. I. p. 152. 



Skeleton of the Trunk of a small Ichthyosaurus in the 



Fig. 5. Nearly flat articular surface of (probably) the third cervical 

 vertebra of the same large Individual as Fig. 3. This surface of the 

 bone has only a small cylindrical depression at its centre, instead of the 

 deep, conical cup of the more flexible vertebrae, C. B. E. 



Near its upper margin is a wedge-shaped elevation (b) and near the 

 inferior margin, a notch or furrow (a.) These salient and re-entering 

 portions articulated with corresponding depressions and projections on 

 the surface of the adjacent vertebra, and acted as pivots, admitting a 

 limited amount of lateral vibrations, and at the same time preventing 

 any slip, or dislocation. 



Fig. 6. Concave surface of Fig. 5. ; the wedge-shaped projection 

 near its lower margin (a) must have articulated with a corresponding 

 groove or depression on the front of the vertebra adjacent to it, like 

 that at (Fig. 5. a.) As one surface only of these vertebrae had a coni- 

 cal cavity, the intervertebral substance must have formed a single cone, 

 admitting in the neck but half the amount of motion, that the double 

 cones of intervertebral matter allowed to the dorsal and caudal verte- 

 bra?, (C. B. E.) where greater flexure was required, to effect progres- 

 sive motion by vibrations of the body and tail. 



These dispositions of the articulating facets of the cervical ver- 

 tebra?, acting in conjunction with the three sub-vertebral wedges be- 

 fore described, afford an example of peculiar provisions in the neck of 

 these gigantic Reptiles, to combine a diminished amount of flexure in 

 this part, with an increased support to their enormous heads. 



It is probable that every species of Ichthyosaurus had peculiar vari- 

 ations in the details of the cervical vertebra?, and subvertebral wedges, 

 and that in each species these variations were modified by age. 



In the Gavial Mr. Mantell has recently observed that the first caudal 

 vertebra is doubly convex, like the last cervical vertebra in Turtles. 

 These peculiar contrivances give to the animals in which they occur 

 increased flexibility of the Tail and Neck. 



