Il CERVICAL VERTEBRAE om 
vertebra there may be a ventral median process, arising of course 
from the centrum, termed the hypapophysis. 
From the sides of the neural arch, or from the centrum 
itself, there is commonly a longer or shorter process on each 
side, known as the transverse process. This is sometimes 
formed of two distinct processes, one above the other; in 
such cases the upper part is called a diapophysis, the lower 
a parapophysis. 
The neural arch may also bear other lateral processes, of 
which one directed forwards is the metapophysis, the other 
directed backwards the anapophysis. 
The series of bones which constitute the vertebral column 
can be divided into regions. It is possible to recognise cervical, 
dorsal, lumbar, sacral, and caudal vertebrae. In the case of 
animals with only rudimentary hind-limbs, such as the Whales, 
there is no recognisable sacral region. The neck or cervical 
vertebrae are nearly always seven in number. The well-known 
exceptions are the Manatee, where there are six, and certain 
Sloths, where there are six, eight, or nine. These rare exceptions 
only accentuate the very remarkable constancy in number, which 
‘is very distinctive of the mammals as compared with lower 
Vertebrata. There are of course abnormalities, the last cervical, 
and sometimes the last two, assuming the characters of the 
ensuing dorsals, by developing a more or less complete rib. 
There are also recorded examples of Bradypus, in which the 
number of cervicals is increased to ten. The characteristics, 
then, of the cervical vertebrae are, in the first place, that they 
do not normally bear free ribs, and that there is a break as a rule 
between the last cervical and the first dorsal on this account. In 
birds, for example, the cervicals, differmg im number in different 
families and genera, gradually approach the dorsals by the 
gradually lengthening ribs. The transverse processes of the 
vertebrae are commonly perforated by a canal for the vertebral 
artery, and are bifid at their extremities. In some Ungulates 
these vertebrae, moreover, approximate to the vertebrae of lower 
Vertebrata in the fact that there are ball and socket joints 
between the centra, instead of only the fibrous discs of the 
remaining vertebrae. 
The first two vertebrae of the series are always very 
different from those which follow. The first is termed the 
