The "body" is the thickest and strongest part. Its upper surface is marked by the impressions of the muscles attached to it. There is generally a transverse and a perpendicular ridge. Often there is a little projection from the middle, which is interesting as a rudiment of the process to which is attached the lingual bone of animals, which runs into the substance of the tongue. Its under surface is slightly excavated, as seen in fig. 2, which shows a transverse section through the centre of the body. Observe, this hollow is not for the attachment of muscles, but for the purpose of making room for the thyroid cartilage to rise behind the os hyoides in deglutition. It is a rudiment of the great cavity which forms the drum in the hyoid bone of the howling monkeys (mycetes). Observe, moreover, that the plane of the body is nearly horizontal, and that the thyro-hyoid ligament is attached to its posterior border.

The greater cornu projects backwards about one inch and a half, not quite horizontally, but with a slight inclination upwards, and terminates in a blunt end tipped with cartilage. Until the middle period of life, the great cornu is united to the body by cartilage; but this ossifies in the progress of age.

The lesser cornu is not much larger than a barleycorn, and projects backwards at an acute angle from the junction of the body and the greater cornu. It articulates with the body by a little. joint, and is freely movable: the stylo-hyoid ligament is attached to the end of it.

The many muscles attached to the hyoid bone are shown in the plate.

The os hyoides is connected to the thyroid cartilage by three ligaments, which contain a large quantity of elastic tissue. These ligaments are:-1. The anterior thyro-hyoid (Plate XLVIII. a, fig. 1), which proceeds from the pomum Adami to the upper part of the body of the os hyoides. 2. The two posterior thyro-hyoid, which extend, one on each side, from the end of the great cornu of the os hyoides to the superior cornu of the thyroid cartilage. The vacant space left in the dried preparation between the hyoid bone and the thyroid cartilage is closed in the recent state by the thyrohyoid membrane.