Fig. 87. Cervical vertebrae of a young Fin Whale

(Balaenoptera musculus) × 1/10. (Camb. Mus.)

1. surface on the atlas for articulationIn the fresh specimen these two
with the occipital condyletransverse processes are united by
of the skull.cartilage, in adult individuals the
2. foramen for exit of the firstwhole transverse process is ossified.
spinal nerve.5. epiphyses of centrum.
3. upper transverse process.6. neural spine.
4. lower transverse process.

In the Cetacea there are invariably seven cervical vertebrae, but they are always very short and are frequently even before birth fused together by their centra into one continuous mass (see fig. 67). Sometimes the last one or two are free. In the Rorquals (Balaenoptera) however, the cervical vertebrae are quite separate and distinct (fig. 87), and in the fluviatile Odontoceti, Platanista, Inia, and Pontoporia, and also in Beluga and Monodon, though very short they are free. In Physeter the first vertebra is free while the others are fused. An odontoid process is not commonly present even in Cetaceans with free cervical vertebrae, but a very short one occurs in the Rorquals. The cervical vertebrae of Rorquals give off on each side two transverse processes (fig. 87, 3 and 4) which enclose between them a wide space. These processes are not completely ossified till the animal is adult.

Fig. 88. Atlas (B) and axis (A) vertebrae of an Ox

(Bos taurus) × ¼. (Camb. Mus.)

1. neural canal.6. anterior opening of the
2. transverse process.vertebrarterial canal.
3. surfaces for articulation with7. foramen for the exit of the
the occipital condyles ofsecond spinal nerve.
the skull.8. neural spine.
4. spout-like odontoid process.9. postzygapophysis.
5. hypapophysis.

In all Ungulata the number of cervical vertebrae is seven. Among the Artiodactyla two forms of the odontoid process of the axis occurs; in the Suina and Tragulina it is conical, in the Ruminantia and Tylopoda it is spout-like (fig. 88, 4). The atlas in the Suina and to a less extent in the Ruminantia has long flattened transverse processes, and the remaining cervical vertebrae are opisthocoelous. Those of the Giraffe and Llama (fig. 103) are noticeable for their great length. In the Tylopoda the posterior half of the vertebrarterial canal is confluent with the neural canal.