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FOSSIL REPTILIA OF THE 



of the arch and centrum than in the PL dolichodeirus (Tab. Ill, fig. 4) or in PL Bernardi 

 (for example, Monograph, 1862, Tab. IV, fig. ] 1), and their articular surfaces are more 

 horizontal, the anterior ones (Tab. X and XI fig. 1, z) looking almost directly- 

 upward, the posterior ones (ib. downward ; in this character the present species 

 resembles the PL liomalospondjjlus. The neural spine is of subrhomboid figure, its 

 height hardly exceeding the fore-and-aft breadth ; the anterior border is convex, and 

 rounded off into the upper one, with a scarcely marked angle ; the posterior one is 

 slightly concave, the angle between it and the upper border is blunted ; the antero- 

 posterior extent of the base of the spine is 1 inch 4 lines, the height of the spine is 

 1 inch 6 lines. The parapophyses (Tab. X, figs. 1 and 3, Tab. XI, fig. 1, pi) are not 

 anchylosed to the centrum. Their head, or articular surface (ib. fig. 2 pi), forms the 

 thickest part ; the bone decreases as it stands outward, especially in vertical diameter, 

 becoming flattened or depressed ; it then bends backward, sending a short process 

 forward, like the tubercle of the Crocodile's cervical rib, but developed from the same 

 plane as the head ; the backwardly contained body of the rib decreases in horizontal 

 and increases in vertical breadth, presenting a broadly convex surface outwardly 

 (Tab. X, fig. 3 pi). The length of the cervical pleurapophysis in the fifteenth cervical 

 here described from the fore part of the head to the posterior point, is 2 inches ; from 

 the end of the tubercle to the posterior point is 1 inch 8 lines. The increase in the 

 succeeding vertebrae is most in the pleurapophyses, next in the neural spines, then in 

 the breadth of the vertebra, and least in the length of the centrum; this, indeed, 

 varies somewhat, but not so much as appears in the figure 2 of Tab. XI, in which 

 the matrix is left upon part of the inferior surface in two of the vertebra?. 



Resuming the consecutive examination of the spinal column we find, in the 

 twentieth vertebra (Tab. XII, 20), the costal surface rises nearer the neurapophyses (np) ; 

 the rib has attained a length of 2 inches 8 lines. In the twenty-first (ib. 21) the 

 costal surface reaches the neurapophyses (np), which contributes a little to its upper 

 part by a diapophysial projection. The vertical extent of this costal surface is 1 inch, 

 the length of the pleurapophysis is nearly 3 inches. In the twenty-second vertebra 

 half the costal surface is formed by the diapophysis. The length of the rib (d) is 

 3 inches 9 lines ; the anterior process or tubercle becoming shortened. It is shorter 

 in the next rib (pi), the body of which is longer ; and on the rib of the twenty-fourth 

 vertebra it has disappeared. In the twenty-fifth vertebra (ib. d 1) the diapophysis (d) 

 is prominent, and forms the entire costal surface. The ribs of this instructive series 

 of six consecutive vertebras have been dislocated from their articulations, apparently 

 by the operation of the pressure which rotated the rest of the vertebras from the 

 vertical to the lateral position, but they retain their relative positions to each other, 

 the end of one extending beyond and below the fore part of the next, and, in a greater 

 degree, as the vertebras approach the back. The sides of the neural spines of these 

 vertebras are roughened by irregular or granulate ridges, directed toward their 



