220 ELEMENTS OF MAMMALIAN ANATOMY. 



is known as the Schneiderian membrane. In a fresh speci- 

 men it is of a grayish color while the other mucous mem- 

 brane is red. The first pair of cranial nerves convey the 

 olfactory impulse to the brain. They pass through the fora- 

 mina in the cribriform plate of the ethmoid bone, to the 

 olfactory bulbs, from each of which two roots extend to the 

 .base of the cerebrum (Fig. 93). 



The Gustatory Organ. The organ of taste is located 

 chiefly in the mucous membrane on the dorsum of the 

 tongue, the soft palate, the pillars of the fauces, epiglottis, 

 and part of the cheek. On the dorsum of the tongue are 

 seen four kinds of papillae the circumvallate, the fungi- 

 form, the filiform, and flat. The circumvallate papillae are 

 from eight to twelve in number, forming two sides of a 

 triangle on the caudal portion of the dorsum of the tongue. 

 The fungi form are blunt papillae scattered sparsely in the 

 midst of the numerous filiform or pointed papillae (Fig. 56). 

 The special organs of taste, known as taste-buds, are very 

 numerous in the fungi form and circumvallate papillae of 

 most mammals, but in the cat they are few and not well 

 differentiated. These tastebuds occur in many parts of the 

 mucous. membrane of the mouth cavity, each being supplied 

 with a branch of the glossopharyngeal nerve. 



The Visual Organ. The special organ of sight is the 

 eye, which occupies the orbital cavity of the skull. The ball 

 of the eye is protected above and below by extensions of 

 skin called the eyelids or palpebrae, which are lined with 

 mucous membrane, a transparent layer of which, known as 

 the conjunctiva, extends over the front of the eyeball be- 

 tween the two lids. The dorsal lid is raised by the levator 

 palpebrae muscle, which has its origin in the occipitofrontalis 

 muscle. A sphincter muscle, the orbicularis palpebrarum, 

 lies on the margin of the lids, and by its contraction closes 

 the eye. 



