OF THE IGUANODON, AND OTHER SAURIAN REMAINS. 
137 
b b. The neurapophysis. 
c c. Oblique processes. >fifteen inches in height. 
d d. Superior spinous process.J 
e e. Transverse processes. 
ff. Hsemapophysis or chevron bone. 
h. Inferior spinous process of the chevron bone. 
The neurapophyses are united to the centrum by suture. The extreme height of the 
superior spinous process, the shortness of the transverse, and the length of the 
chevron bones, prove that the tail must have been largely developed in a vertical 
direction ; its height could not have been less than twenty-seven inches. The hsema- 
pophyses are of the same form, and articulated to the body of the vertebrae in like 
manner, as in the Iguana. 
An atlas of a young individual is highly characteristic of the Lacertian type; and in 
this specimen (Plate IX. fig. 1.) the form of the medulla oblongata (a a) is preserved in 
a cast of calcareous spar, which fills up the cavity once occupied by this portion of 
the medullary column. 
Ribs, or costal processes. — Fragments of ribs occur in great abundance, and a few 
well-marked specimens have been preserved ; these are bilobed or bifurcated at the 
proximal or spinal extremity. One example is four feet in length, and yet it is 
evidently not more than one-half of the bone ; the width across the arch is four inches 
near the spinal termination. From numerous slender bones in the Maidstone speci- 
men, there appears reason to conclude that the distal extremities of the ribs were con- 
nected together in the abdominal region by a series of elongated processes. 
Pectoral arch. — Several bones, evidently referable to a complicated sternal appa- 
ratus, approximating to that of the Lizard family, were discovered many years since, 
and one of these, of a very extraordinary form, was figured and described in the 
* Fossils of Tilgate Forest,’ and in the f Geology of the South-East of England*,’ under 
the provisional name of clavicle This bone (see Plate VIII. figs. 18, 19.) is long, 
slender, and slightly arched ; of a prismatic form in the middle, and enlarged and 
flat at both ends. At the distance of not quite one third from the widest extremity, 
a small apophysis (Plate VIII. figs. 18, 19. c c) is sent off ; the bone then enlarges, and 
terminates in two unequal flat processes (Plate VIII. figs. 18, 19. a, b). A perfect spe- 
cimen in the British Museum is twenty-eight inches long; and there are portions in- 
* Geology of the South-East of England, plate iv. figs. 1, 2. 
f The sternal apparatus of the Lizards is very peculiar, and much more complicated than that of the Croco- 
diles. The sternum is a long narrow depressed bone, which gives out two lateral branches, and between which 
its point sometimes passes and proceeds more in front under the neck. There is also a still greater difference in 
the development of the coracoid, and in the constant presence of a clavicle. The coracoid furnishes nearly one- 
half of the glenoid cavity, and gives out one or more apophyses to support a large cartilaginous arch which passes 
over the narrow bone in front of the sternum, and crosses with that of the coracoid on the other side. There is 
always a foramen for the vessels, pierced in the neck of the bone, between its apophyses and the glenoid facet. 
The omoplate forms the other portion of the glenoid cavity ; in the middle, or at about one-third of its length, the 
osseous part suddenly terminates, and is continued by a cartilaginous portion ; this frequently becomes ossified, 
and then the omoplate is constantly divided into two bones. — Cuvier, R'egne Animal. 
