CARNIVORA. In Carnivora vera the most striking feature of the malleus is the occurrence of a broad lamellar expansion between the head and neck and the processus longus. This however does not occur in some Viverridae. In the Carnivora vera the incus and stapes are small as compared with the malleus, but in the Pinnipedia they are large. In the Pinnipedia the auditory ossicles have a very dense consistence, and except in the Otariidae are very large. The stapes frequently has no canal, or only a very small one. In INSECTIVORA the characters of the auditory ossicles are very diverse. Many forms such as shrews, moles, hedgehogs, and the Centetidae have a low type of malleus resembling that of Edentates. _Chrysochloris_ has very extraordinary auditory ossicles. The head of the malleus is drawn out into a great club-shaped process, the incus is long and narrow, and differs much from the ordinary type. In CHIROPTERA the ossicles and especially the malleus much resemble those of shrews. The stapes is always normal in character, never becoming at all columelliform. PRIMATES. In Man and the Anthropoid Apes the malleus has a rounded head, a short neck, and the manubrium, a processus longus and a processus brevis. The incus consists of an anvil-shaped portion from which arises a long tapering process. The stapes has diverging crura and consequently a wide canal. The crura in other monkeys do not diverge so much as in man and anthropoid apes. The New World monkeys have no neck to the malleus. THE STERNUM[168]. In MONOTREMES and most MARSUPIALS the sternum does not present any characters of special importance. The presternum is strongly keeled in _Notoryctes_. The sternum in EDENTATES is very variable: in the Sloths it is very long, the mesosternum of _Choloepus_ having twelve segments. In the ant-eaters and armadillos the presternum is broad and sometimes as in _Priodon_ strongly keeled. In _Manis macrura_ the xiphisternum is drawn out into a pair of cartilaginous processes about nine inches long. In the SIRENIA the sternum is simple and elongated, and of fairly equal width throughout, in the adult it shows no sign of segmentation. Its origin from the union of two lateral portions can be well seen in _Manatus_. Two distinct types of sternum are met with in the CETACEA. In the Odontoceti the sternum consists of a broad presternum followed by three or four mesosternal segments, but with no xiphisternum. Indications of the original median fissure can be traced, and are very evident in _Hyperoödon_. In the Mystacoceti, on the other hand, the sternum consists simply of a broad flattened presternum which is sometimes more or less heart-shaped, sometimes cross-shaped. Only a single pair of ribs are united to it.