Vertebral formula of Ziphius cavirostris.
| Locality and sex. | C. | Th. | L. | Ca. | Total. |
|---|---|---|---|---|---|
| Newport, Rhode Island, male | 7 | 9 | 10 | 20 | 46 |
| Barnegat City, New Jersey, female | 7 | 9 | 11 | 18(+1?) | 46(?) |
| Charleston, South Carolina, female | 7 | 10 | 10 | 16(+3?) | 46(?) |
| Holma, Sweden (Malm) | 7 | 10 | 10 | 18(+1) | 46 |
| Pisa Museum (Van Beneden) | 7 | 9 | 11 | 16+ | 43+ |
| Warrington, New Zealand (Scott and Parker) | 7 | 10 | 9 | 20 | 46 |
| Lyttleton Harbor, New Zealand (Haast) | 7 | 9 | 11 | 19 | 46 |
| Buenos Ayres, Argentina (Burmeister), male | 7 | 10 | 10 | 22 | 49 |
In the figures of the Argentine specimen the last ten caudals are practically without characters, and it is perhaps allowable to question whether the terminal two or three were not added to make an even taper to the end of the column. If such be not the case, this specimen had more vertebræ than any other.
CHARACTERS OF THE VERTEBRÆ.
Newport (male).—The seventh cervical vertebra presents a conical metapophysis, which on the first thoracic vertebra forms of a rather thick, long, declining process ending in a facet for the tubercle of the first rib. This metapophysis maintains nearly the same form as far as the sixth thoracic vertebra, but on the third thoracic a mammiliform process makes its appearance on the anterior margin near the tip, and becomes more prominent on each succeeding vertebra. On the seventh thoracic it becomes larger, thin, and upright, and widely separated from the articular facet for the tubercle of the rib. On the centrum of this vertebra lower down is a second much larger rugose articular facet. On the eighth thoracic vertebra the upper articular process disappears altogether and is replaced by a transverse process on a lower level, with a facet at the free end for the rib. On the ninth thoracic the transverse processes are larger and nearly straight. They are longer on the first lumbar and incline a little forward. Those of the succeeding vertebræ are similar, but decrease gradually in length, while somewhat increasing in breadth. They are last traceable on the ninth caudal. On the eighth caudal they are perforated by a foramen.
All the vertebræ from the first cervical backward have neural spines as far as and including the eleventh caudal. The spine on the first thoracic is rather short, narrow and pointed. These spines increase in height in succeeding vertebræ as far as the sixth lumbar; at the same time the breadth increases antero-posteriorly and the tip becomes expanded. The spines are nearly equally high on all the succeeding lumbars, but begin to decrease on the caudals and disappear altogether on the eleventh caudal.
The anterior zygapophyses and metapophyses maintain a nearly constant position close to the top of the centra throughout the column, from the seventh thoracic backward, and are vertical, thin, and oblong, squared or rounded. They begin to decrease in size noticeably on the first caudal, and on the seventh caudal are mere swellings at the sides of the nearly horizontal plate from which the neural spine springs. They are traceable as far as the twelfth caudal.
A ridge appears on the side of the neural arch near its base on the fifth caudal and is stronger and very marked on those following, to the ninth caudal. A ridge unites the anterior and posterior facets for the chevrons on the ninth and succeeding caudals.
Barnegat City (female).—Unlike the Newport skeleton, there are no neural spines on the fifth, sixth, and seventh cervicals. The spine on the first thoracic vertebra is quite short and sharp, and on the second, third, and fourth thoracics also is rather pointed, though of increased length. There is no metapophysis on the seventh cervical.
On the seventh thoracic the facet for the tubercle of the rib, instead of being very prominent, becomes inconspicuous. The metapophysis is flat and squared, and there is no lower facet on the side of the centrum. On the eighth thoracic the metapophysis is thin, squared, and vertical, and a well-formed transverse process appears on the side of the centrum. The transverse processes of the ninth thoracic are a little curved backward, and on the first lumbar and succeeding vertebræ bent forward. These processes are less tapering on all the lumbars than in the Newport skeleton. They disappear on the eighth caudal. None is perforated.