LOWER LIAS. 5 



lengthens in the seventh cervical; but the ordinary rib-shape is only resumed in 

 the eighth vertebra, regarded as the first dorsal by Cuvier. 



I infer, therefore, from the size and proportions of the two vertebrae 

 just described that they correspond with the sixth and seventh in the Croco- 

 dile, and that the Scelidosaurus, with probably other Dinosauria, differed from 

 Crocodilia and from most Lacertilia in the long and slender form of most, if not 

 all, of the cervical ribs; but that these manifested their more essential Crocodilian 

 affinity in their twofold articulation, by a bifurcate head, with distinct upper and 

 lower transverse processes. 



The fourth block of Lias includes, with the scapular arch, ten of the anterior 

 dorsal vertebrae (Tabs- II and III). The hinder fracture of the block has detached 

 the anterior articular surface from the eleventh dorsal, the rest of which is the first 

 of the series of the five following dorsals in the fifth block of Lias (Tabs. IV 

 figs. 1 and 2). The hinder fracture of this block has pretty equally bisected the last 

 vertebra, which bears free ribs, viz., the sixteenth dorsal, the hinder half of which 

 remains in the fore part of the block (Tab. VI), including the lumbar and 

 sacral series of vertebrae. The section of the eleventh dorsal thus exposed near 

 the anterior articular surface of the centrum is represented of the natural size in 

 Tab. V, fig. 1, d ii. That through the middle of the sixteenth dorsal vertebra is 

 similarly represented in Tab. V, fig. 2, d 16. 



The spinous process of the first dorsal vertebra (Tab. II, d l) is 1^ inch in 

 height and 8 lines in fore-and-aft extent; the spine increases in both directions to 

 the fifth of these vertebrae (5), which is 2 inches 4 lines in height and 1 inch 10 

 lines in basal extent. The spines continue of about the same height to the tenth 

 vertebra, d 10, with summits obtusely rounded, almost truncate. In the eleventh 

 to the sixteenth dorsals, Tab. IV, d 11 — d ig, the spines acquire their greatest fore- 

 and-aft extent, with truncate summits, but no increase of height. Although these 

 spines in the last six vertebrae are nearly 2| inches in antero-posterior extent, their 

 summits do not come into contact, but leave interspaces of from 5 lines to 8 lines. 



The prezygapophyses in the anterior dorsal vertebrae look inward and a little 

 upward, the postzygapophyses in the reverse directions, but as the vertebrae 

 recede in position the aspect of the surfaces becomes more nearly horizontal 

 (Tab. V, fig. 1, s ). The diapophyses are subdepressed, 10 lines in breadth in the 

 second vertebra, and gradually increasing to a terminal breadth of 15 lines in the 

 ninth and tenth dorsals Tab. II, d, d- The parapophyses, as in the Crocodile, gradu- 

 ally pass from the centrum to the neural arch, and are seen at p, fig. 1, Tab. V, upon 

 the under and fore part of the diapophysis {d ) in the eleventh of this series of 

 dorsals, where the length of the diapophysis from the base of the neural spine is 

 2 inches 9 lines. No trace of parapophysis, or of the " head" of the rib, remains 

 in the last three dorsals ; the diapophysis is entire, as at d, fig. 2, Tab. V. 



