344 MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 
tenth, and’ absent in the eleventh caudal vertebra; in the Yorkshire skeleton it is 
indicated by a ridge in the eighth, and is completely wanting m the ninth; so that in 
this respect the Tasmanian specimen holds an intermediate position between the two 
northern ones. ; 
On the hinder edge of the transverse process of the fifth caudal vertebra, close to its 
origin from the body, is a deep notch, for the passage of a blood-vessel; in the two fol- 
lowing vertebre this notch increases in depth, being continuous with a vertical groove on 
the side of the body of the bone. In the eighth the notch is enclosed so as to form a 
large oval foramen 385" by 3%5" in diameter, perforating the base of the transverse process, 
rather behind the middle of the centrum. In the ninth vertebra the foramen is placed 
nearer the median line, and therefore still further enclosed in the bone. It is here and 
in the succeeding vertebra nearly midway between the anterior and posterior extremity. 
This foramen is an important feature in all the remaining caudal vertebre, being found 
even in the penultimate, and presents several peculiarities worthy of note. As before 
said, it first appears as a distinct foramen in the eighth vertebra; or it may rather be 
described as a broad vertical groove on the side of the centrum, bridged over for a space 
of 24” by the base of the short transverse process. In the tenth vertebra it has become 
a canal, 7” in length; but the lower opening is still placed on the side of the body of 
the vertebra. In the eleventh the lower opening is placed at the angle between the 
side and the inferior surface, 5” from the opening of the canal of the opposite side. In 
the twelfth they have moved toward the middle of the inferior surface, being separated 
from each other only by a narrow bony septum (less than 1" in width). In the next 
three vertebra the septum is still narrower ; in the sixteenth it suddenly widens to 2"; and 
thence onward the inferior openings are gradually placed rather further from each other, 
until in the last few vertebree the canals have gained the lateral position they possessed 
on their first appearance. In the meanwhile the upper orifices of these canals, advancing 
up the sides of the bodies of the vertebrae, soon come to be placed on each side of the 
middle of the upper surface, and maintain this situation to the end, only approaching 
nearer to-each other as the vertebree diminish in size. 
The articular surfaces for the chevron bones are remarkably large and prominent, 
with elevated edges, and rough cup-like depressions in their middle. In many of these 
depressions a small, loose, irregular epiphysial plate is lodged. ‘The first caudal ver- 
tebra has a pair of subcircular facets at its hinder edge, of which the left is considerably 
the larger, though somewhat less prominent; to these the first (ununited) heemapophyses 
fit closely. In the Caithness Cachalot, these bones are ankylosed to the body of the 
vertebra, though not meeting each other at their free ends. In the second vertebra, 
the hinder facets are of larger size; but none are developed on the anterior edge. In 
the third, the facets on the anterior edge are slightly indicated, the posterior ones have 
increased still more. In the following nine vertebrz, the two pairs of facets are well 
developed, the anterior ones at first comparatively small, but towards the end of the 
