458 
Thame, in the collection of Dr. Buckland: Mr. Owen has likewise 
examined a vertebra and some bones of the extremities of the same 
saurian from the Yorkshire oolite, and preserved in the Scarborough 
Museum. 
Caudal Vertebre.—A caudal vertebra from near Buckingham, 
which presented the anchylosed neural arch entire, but with the 
transverse, oblique and spinous processes broken off, equalled in di- 
mensions a middle caudal vertebra of a full-sized whale, the antero- 
posterior diameter being five inches, the transverse eight inches six 
lines, and the vertical seven inches. The sides and under part of 
the centrum are described as very concave; and the shape of the 
articular extremities as nearly circular, with a greater concavity in 
the anterior one than in the posterior. The posterior heemapophysial 
articular surfaces slope downwards and forwards in the form of semi- 
circular facets for nearly two inches upon the under surfaces. The 
neurapophyses commence close to the anterior surface of the cen- 
trum, their antero-posterior extent being three and a half inches, 
and they meet at a rather acute angle above the spinal canal. The 
vertical diameter of the spinal canal was one inch nine lines, the 
transverse two inches, and the breadth of the base of the neural arch, 
from the outside of the neurapophyses, five inches three lines. The 
transverse process is developed from the centrum just below the neu- 
rapophysial suture. In all the caudal vertebre of the Cetiosaurus 
the posterior half of the centrum is left uncovered by the neural arch. 
The substance of another fractured vertebra, showing the upper 
third of the centrum, presented an uniform coarse spongy texture ; 
whilst in a third specimen, which exhibited also a similar texture, 
the layers affected a direction parallel with the articular extremities 
for about half an inch from their surfaces, and inclined to the longi- 
tudinal course in the intermediate space. This structure, Mr. Owen 
states, proves that the vertebra cannot belong to the Pozkilopleuron 
Bucklandi. 
A caudal vertebra also from Buckingham, and assigned by Pro- 
fessor Owen to the middle part of the tail, on account of the de- 
velopment of short, narrow transverse processes just below the 
neurapophysial sutures, exhibited a centrum of a subtrihedral form, 
with one angle inferiorly and the other two at the origin of the 
transverse processes, but all three largely rounded off. The marginal 
circumference of the centrum was convex, and separated from the 
lateral or free surface by a rough, irregular, elevated ridge, the in- 
ferior part of which encroached upon the under surface of the ver- 
tebra in the form of two semicircular facets, both anteriorly and 
posteriorly. The free surface of the vertebral centre is marked by 
the coarse lines of the bony fibrous structure, decussating like an 
irregular net-work. The spinal canal of this specimen did not sink 
into the body of the vertebra. The size of this vertebra, and the 
proportions and position of neurapophyses and hemapophysial arti- 
culations, might suggest a relationship of the animal to which it 
belonged with the Cetacea; but it differs, Mr. Owen says, in the 
concavity of the terminal articulations, which show no sign of sepa- 
ration as laminar epiphyses, and more particularly in the place of 
