The mandible is rather short and broad, and the angle formed by the meeting of the two rami is more obtuse than in most mammals. The coronoid process is fairly well developed, and the angle is more or less rounded. In most Primates the condyle is considerably widened, but this is not the case in Man. In _Mycetes_ the mandible is very large, its ascending portions being specially developed. The hyoid of Primates is remarkable for the large expanded basi-hyal, which is generally concave above and convex below. The anterior cornu is never well ossified, but the thyro-hyal is always strong. In _Mycetes_ the basi-hyal is enormously large, forming a somewhat globular thin-walled capsule. AUDITORY OSSICLES. [Illustration FIG. 100. MALLEUS, STAPES AND INCUS OF _A._ MAN. _B._ DOG. _C._ RABBIT. (After DORAN) x 1. 1. head of malleus. 2. canal of stapes. 3. incus. 4. processus longus (or gracilis). 5. manubrium of malleus. 6. processus brevis. 7. lamella.] There are in mammals four auditory ossicles forming a chain extending from the fenestra ovalis to the tympanic membrane. Three of these, the =malleus=, =incus= and =stapes=, are always distinct, while the fourth, the =lenticular=, is smaller than the others and is sometimes not distinct. The names are derived from human anatomy and indicate in the case of the first three a more or less fanciful resemblance respectively to a hammer, an anvil and a stirrup. The ossicles are homologous as a whole to the hyomandibular of fishes and to the columellar chain of Sauropsids and Amphibians. The malleus is homologous to the extra-columella of Crocodiles and the stapes to the columella. The =malleus= when typically developed consists of a rounded _head_ (fig. 100, 1) which bears a surface articulating with the incus, and a short _neck_ continued into a process, the _manubrium_ (fig. 100, 5), which comes into relation with the tympanic membrane. From the junction of the neck and manubrium two processes are given off, a _processus longus_ or _gracilis_ (fig. 100, 4), which in the embryo is continuous with Meckel's cartilage, and a _processus brevis_ (fig. 100, 6). The =incus= generally consists of a more or less anvil-shaped portion which articulates with the malleus, and of a process which is connected with the stapes by the small =lenticular=. The =stapes= is generally stirrup shaped, consisting of a basal portion from which arise two _crura_ separated by a space the canal through which a branch of the pharyngeal artery runs The lenticular is frequently cartilaginous and sometimes is not developed at all. The above is the arrangement of the auditory ossicles met with in the higher Mammalia, but in the lower Mammalia the characters approach more nearly to those met with in Sauropsids.