. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 542 RUMINANTIA. by the inferior thyroideal only, the superior being distributed to the larynx. In the fore- limb, a vascular twig, corresponding to the interosseous artery, is present both in the Ruminants and Solipeda ; it is very voluminous in the former, and but faintly marked in the latter. The common carotids are remarkable for their length in certain individuals ; the most interesting peculiarity, however, obtains in the presence of numerous anastomising branches given off by, and tortuously inter- communicating be
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 542 RUMINANTIA. by the inferior thyroideal only, the superior being distributed to the larynx. In the fore- limb, a vascular twig, corresponding to the interosseous artery, is present both in the Ruminants and Solipeda ; it is very voluminous in the former, and but faintly marked in the latter. The common carotids are remarkable for their length in certain individuals ; the most interesting peculiarity, however, obtains in the presence of numerous anastomising branches given off by, and tortuously inter- communicating between the internal carotids. It is this plexus which has been long known under the name of rete mirabile, being situated within the cavernous sinus on either side of the sella turcica, and occasionally extending backwards to join the vertebral artery. Simi- lar appearances are found in Carnivora, and in Cetacea where they are are not confined to the region of the cranium ; many other ano- malies of the same kind occur in other fami- lies, the most striking being seen in the Sloth, where the brachiah and femorals are split up, as it were, into numerous hair-like capillaries. The spermatic artery is exceedingly large in the Bull and twisted into a multitude of con- volutions. In regard to the venous system of ruminants we have only to remark that, ac- cording to Weigel, valves are developed in the portal vein.* Organs of respiration. — The structural modifications observable in this system de- Fig. part so slightly from the ordinary mammi- ferous type as scarcely to call for a separate notice. The organisation of the larynx is simple, its anterior ligaments and ventricles being absent ; in many species the thyroid cartilage is comparatively narrow. The tra- cheal rings are for the most part incomplete, and vary numerically in accordance with the length of the neck. According to Meckel there are fifty in Moschus ; sixty in the Stag ; seventy in the Chamois, Ox, and Sheep; eight
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