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. [Illustration FIG. 88. ATLAS (B) AND AXIS (A) VERTEBRAE OF AN OX (_Bos taurus_) × 1/4. (Camb. Mus.) 1. neural canal. 2. transverse process. 3. surfaces for articulation with the occipital condyles of the skull. 4. spout-like odontoid process. 5. hypapophysis. 6. anterior opening of the vertebrarterial canal. 7. foramen for the exit of the second spinal nerve. 8. neural spine. 9. postzygapophysis.] 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. The Perissodactyla have remarkably opisthocoelous cervical vertebrae. Those of _Macrauchenia_ have the posterior half of the vertebrarterial canal confluent with the neural canal as in Tylopoda. In the Proboscidea they are short flattened discs slightly opisthocoelous; the axis and seventh vertebra and to a less extent the sixth have high neural spines. In the RODENTIA the atlas generally has broad wing-like transverse processes, and the axis a large and long neural spine, while the odontoid process is much developed. In the Jerboas (_Dipus_) all the cervical vertebrae except the atlas are fused together, a condition recalling that in armadillos.