LOWER LIAS. 7 



physial (pi) with the par- and di- apophyseal elements of this part. It is 4| inches 

 in length ; at its base it is 1 inch in thickness and 2 inches in depth, expanding in 

 that direction to fully 3 inches at the truncate extremity, and in breadth to 2 inches 

 2 lines. Towards its end the process is excavated anteriorly, so that the rough 

 terminal surface (fig. 2, pi.) abutting upon the iliac bone is reniform. Fracture of 

 an angle of this surface in the left transverse process shows a medullary cavity of 

 10 lines in diameter by 6 lines in the section as exposed, surrounded by a fine 

 cancellous, almost compact, osseous texture, of from 2 lines to 4 lines in thickness. 



The transverse processes of the other sacral vertebrae gradually become shorter, 

 with corresponding decrease of breadth at their origin, but with equal or greater 

 expansion of their termination, that of the last (pi, s 4) measuring 2 inches 7 lines 

 in fore and aft breadth ; the transverse processes thus touch each other, or nearly 

 so, at their ends, and offer a continuous longitudinal surface for the ligamentous 

 or fibro-cartilaginous attachments of the iliac bones (62). The total length of the 

 articular " sacro-iliac" tract, so formed, is about 10 inches ; a very slight lateral twist 

 or dislocation makes it rather longer on the left than on the right side ; this appears 

 to have been due to great pressure after imbedding, and is accompanied by frac- 

 ture or dislocation of the pleurapophysial part of the transverse process of the last 

 two sacral vertebrae. 



The spinous process, in each of the four sacrals, is about 2 inches high and 

 2 inches 3 lines in fore and aft extent : they touch each other by their rough, 

 flattened summits; these are narrow anteriorly, gradually expanding to a breadth 

 of 8 lines at their posterior third, with a thick, rounded termination ; the position of 

 these spines is over the interspaces of the origins of the transverse processes, 

 through the backward inclination or extension of the neural arches. The articular 

 processes are faintly indicated at their base, the posterior processes overlapping 

 the anterior ones of the succeeding vertebra. The longitudinal extent of the 

 truncated summits of the four sacral spines is 9 inches. 



The hinder fractured surface of the block containing the sacrum exposes part 

 of the first caudal vertebra, the rest being associated with the four consecutive 

 caudals in the seventh block of Lias (Tab. VII, figs. 1 and 2). 



The first caudal vertebra has been dislocated from the last sacral, and twisted 

 half round, so that its spine lies upon the sacral transverse process; the fracture 

 has passed through the spine and part of the neural arch. The length of this 

 spine (Tab. VII, fig. 1, «*) from the upper part of the neural canal is 3 inches 6 

 lines, the transverse process (d) is 2 inches 3 lines in length, but its vertical thick- 

 ness is reduced to 5 lines at 2 inches from its termination. The neural canal is 

 6 lines in breadth and 10 lines in depth. The bases of the neural arch seem to 

 show that the anchylosis with the centrum had not here been complete. 



The length of the first caudal centrum (Tab. VII, c 1) is 2 inches, the depth or 



