156 SKELETON OF THE SHEEP 
The large metatarsal bone is usually regarded as consisting of the fused third and fourth 
metatarsal bones, and the small bone as the second metatarsal. The medullary cavity is subdivided 
like that of the large metacarpal bone. Some anatomists, however, consider that the ridges at 
the upper end of each border represent the second and fifth metatarsals (Rosenberg and Retterer). 
On this basis the small bone would be the first metatarsal. 
The phalanges and sesamoids resemble those of the thoracic limb so closely 
as to render separate description unnecessary. 
SKELETON OF THE SHEEP 
VERTEBRAL COLUMN 
The vertebral formula may be given as C7Ti3L5_7SyCyigis, but it should be 
noted that, except in the cervical region, variation in number is common. 
It is not very rare to find twelve thoracic and seven lumbar, or an ambiguous intermediate 
vertebra. More commonly there are seven lumbar vertebre without reduction in the thoracic 
region. In some cases there are fourteen thoracic and five or six lumbar vertebrae, and Lesbre 
records a case in which twelve thoracic and seven lumbar were present. In some cases the fourth 
sacral vertebra remains separate, and in others the first coccygeal unites with the sacrum, although 
the fusion here is rarely complete. Nathusius states that the number of coecygeal vertebrie 
varies from three to twenty-four or more. 
The cervical vertebra are relatively longer than those of the ox. The atlas 
differs chiefly in that the prominence on the dorsal arch is much less developed. 
The anterior articular cavities are often separated by a central ridge. The wings 
are produced to form blunt points behind. The spinous process of the axis is not 
enlarged posteriorly; those of the succeeding vertebra are less developed than in 
the ox; they increase in length from the third to the last. The ventral spines are 
rudimentary. The arches are separated dorsally by interarcuate spaces. 
The thoracic vertebre are usually thirteen in number, but fourteen may be 
present, or, more rarely, only twelve. Their bodies are relatively wider and less 
constricted than those of the ox, and their extremities are not so strongly curved, 
especially toward the end of the series. The intervertebral foramina are larger, in 
correlation with the absence of the foramina which usually occur in the arches of 
these vertebrae in the ox. 
The lumbar vertebre number six or seven, the former being a little more fre- 
quent than the latter. It is not common to find the number reduced to five. In 
some cases there is an ambiguous vertebra at the junction of the thoracic and lum- 
bar regions. The bodies are more flattened dorso-ventrally than those of the ox; 
their anterior ends are somewhat concave transversely, and the posterior ends are 
almost flat. The anterior articular processes are strongly curved and overlap the 
posterior ones. The transverse processes curve forward and have expanded ends. 
The sacrum consists ordinarily of four segments, but the last vertebra may re- 
main separate or undergo only partial fusion. There is no vascular groove on the 
pelvic surface. The spines are not fused, with the exception of the first and second, 
which may be partially united. The transverse processes of the last segment are 
distinct and outstanding. 
The coccygeal vertebre vary in number from three (in short-tailed sheep) to 
twenty-four or more. The bodies have no hemal processes on the ventral surface. 
The transverse processes are long and thin and project backward. 
THE RIBS 
The ribs usually number thirteen pairs, but the occurrence of fourteen pairs is 
not at all uncommon. The thirteenth rib is floating and has a cartilage about an 
