LOWER LIAS. 
5 
lepgthens 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 Dmosauria, 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 11 . That through the middle of the sixteenth dorsal vertebra is 
similarly represented in Tab. V, fig. 2, d ig. 
The spinous process of the first dorsal vertebra (Tab. II, d i) is 1^ inchin 
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 vertebrie look inward and a little 
upward, the postzygapophyses in the reverse directions, but as the vertebrie 
recede in position the aspect of the surfaces becomes more nearly horizontal 
(Tab. V, fig. 1, A- The diapophyses are subdepressed, 10 lines in breadth iu 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 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. 
