78 THE ANATOMY OF YERTEBRATED ANIMALS. 



cess is directly continued, and it is liard to say whetlier the 

 styloid part of the hyoid is continued into the incus by these 

 ligaments or by the stapedius. But, however this may be, the 

 inalleus and the incus are the proximal ends of the mandibular 

 and hyoidean arches respectively. 



In osseous fishes (C, Fig. 24), which have no fenestra ova- 

 lis or stapes, the supra-stapedial part- of the hyoid becomes a 

 large bone — the hyomandibular. On the other hand, the 

 proximal extremity of the quadrate cartilage atrophies, loses 

 its direct connection with the periotic capsule, and becomes 

 distinctly ossified, as the metapterygoid. In the Sharks, even 

 the ascending, metapterygoid, part of the quadrate, is lost. 



The quadrate and supra-stapedial portions of the first and 

 second visceral arches coalesce in the Chimcera^ Dipnoi^ and 

 many AmpJiihia^ into a single cartilaginous plate. 



In the JSIaintnalia^ and to some extent in Aves^ osseous 

 matter is deposited in the fibrous tissue wdiich surrounds the 

 sides and base of the tympanic membrane, and gives rise to a 

 special tymjxmiG bone. In most Mammalia^ ossification ex- 

 tends into the sides and floor of the tympanum and external 

 meatus ; and a process of integument, chiefly derived from the 

 second visceral arch, is converted into a concha^ or external ear. 



The Organ of Taste is the mucous membrane which covers 

 the tongue, especially its posterior region, and probably also 

 a part of thatlining the fauces. When the sense is well de- 

 veloped, the mucous membrane is raised into numerous papillae 

 of various forms, and is well supplied with filaments from the 

 glossopharyngeal nerve. 



The sense of Touch is difi'used over the integimient and 

 over the mucous membrane of the buccal cavity, which is, 

 strictly speaking, a part of the integument. 



As special organs of touch in the higher Vertehrcita, the 

 nervous papilla?, containing " tactile corpuscles,'''' and the long 

 facial hairs, the papillae of which are well supplied with nerves, 

 termed vibrissce, may be mentioned. 



In most, if not all Fishes, the integument of the body and 

 of the head contains a series of sacs, or canals, usually disposed 

 symmetrically on each side of the middle line, and filled with 

 a clear gelatinous substance, ^he w^alls of the sacs, or canals, 

 are abundantly supplied with nerves, and the terminations of 

 the latter enter rounded papillce, which project into the gelati- 

 nous contents. These sensory organs are known as the " or- 



