LTASSIC DINOSAURS. 107 



lines in length ; the transverse process (ib., fig. 1, d) to 1 inch 3 lines. The haemal 

 arch and spine retain a length of 3 inches 3 lines. That of the seventh vertebra 

 (fig. 1, h) has a basal diameter of 1 inch 1 line, decreasing to 6 lines at the end of 

 the neural canal, and thence to a terminal diameter of 2^ lines, the fore-and-aft 

 diameter being here 10 lines. The centrums progressively become more concave 

 and compressed between the articular ends. The prezygapophyses (ib., fig. 2, z) 

 have their articular surface turned more inward, and grasp, as it were, the 

 shortening rudiments of the postzygapophyses, the neural arch progressively 

 contracting in breadth. The collective length of the five vertebrae in this block is 

 11 inches. 



The ninth block of Lias contains the five succeeding caudals (PI. 55, fig. 3). 

 The centrums, exposed at their under and lateral parts, are singularly crushed, 

 the sides of each having been pressed into the substance ; yet, where the cracks 

 of the matrix expose the texture of the centrum, as in the fifteenth caudal (PI. 52, 

 fig. 3), it shows a fine, compactly cancellous structure throughout; there is no 

 trace of any such vacuity or unossified nucleus of the centrum as is met with in 

 the vertebrge of Poildlopleuron, for example. The centrums retain their length 

 of 2 inches. The hinder articular end of that of the tenth caudal (c) adheres to 

 the fore part of the present block. In the next coarticulated vertebra, which 

 is the eleventh of the caudal series (PI. 55, fig. 8, ll), the prezygapophysis 

 (ib., fig. A, z) is 10 lines in length and 3 lines in breadth; the neural spine, 

 measured from the base of the zygapophysis, is 2 inches in length ; the transverse 

 process (fig. 3, d) is 1 inch in length, with half an inch of basal breadth. Nearly 

 2^ inches of the hsemal arch (ib., /;) are preserved. 



The pressure crushing the centrum of the eleventh vertebra has been applied 

 to the middle of the under and lateral part; the articular ends have withstood, 

 if they have received, it. The same is the case with the twelfth caudal. In the 

 thirteenth the pressure has been more laterally appUed, and the outer wall, which 

 has been driven in, preserves its vertical convexity. The diapophysis of this 

 vertebra is 10 lines in length. In the fifteenth caudal (ib., 15, d) the diapophysis 

 is reduced to 6 lines in length, with corresponding decrease of thickness. The 

 five caudal vertebrge from the eleventh to the fifteenth inclusive occupy a longi- 

 tudinal extent of 11 inches 6 lines. 



The tenth mass of Lias, fitting on to the foregoing, includes a consecutive 

 series of nine vertebrge, viz. the sixteenth to the twenty-fourth caudal inclusive 

 (PI. 56, fig. 1). In this series there has been a dislocation of the eighteenth 

 from the nineteenth, and a similar one between the twenty-first and the twenty- 

 second vertebrge, with an interval of nearly an inch between the separated 

 articular ends of the centrums. These elements continue to decrease in vertical 

 and transverse diameters, and also, but in a minor degree, in regard to their 



