534 THE RABBIT CHAP. 



taste-buds, are present on the papillae of the tongue (p. 509) 

 and on the soft palate (compare pp. 179 and 180). 



The organs of smell are situated in the olfactory capsules, 

 the form of which has already been described (p. 493). 

 They open externally by the external nostrils, and are pro- 

 duced backwards above the palate into the passage of the 

 internal nostrils, which communicate with the naso-pharynx 

 (Fig. 135 i. n, n. ph, p. 512). The olfactory epithelium, 

 supplied by the olfactory nerves, is situated on the ethmo- 

 turbinal (e. tb) : the mucous membrane of the maxillo-tur- 

 binal (m. tb) probably serves merely to warm the inspired air. 



On the ventral side of the nasal septum is a pair of small, tubular 

 structures known as the vomero-nasal oxjacobsorfs organs (Fig. 135,7), 

 lined by epithelium and enclosed in cartilages situated just to the inner 

 side of the palatine processes of the premaxillse (p. 494). Each of 

 them opens anteriorly into the corresponding naso-palatine canal 

 (p. 507), and receives a special branch of the olfactory nerve. The 

 function of these organs is not understood. 



The structure of the eye (Fig. 57) is similar to that already 

 described in other Vertebrates (pp. 181 and 465), except that 

 the sclerotic is not cartilaginous, but is composed of dense 

 fibrous tissue, and the lens is relatively smaller than in the 

 dogfish and frog and is markedly biconvex in form, the outer 

 surface being rather flatter than the inner : it is capable of 

 adjustment by means of the ciliary muscles contained in the 

 radiating ciliary processes into which the choroid is thrown 

 just externally to the iris (compare p. 184). 



The eyelids have already been described (p. 486). The four recti 

 muscles ensheath the optic nerve, as in the frog (p. 186, compare Fig. 

 126), but the superior oblique, instead of arising like the inferior oblique 

 in the anterior part of the orbit, takes its origin further back, near the 

 recti, passes forwards through a fibro-cartilaginous pulley at the anterior 

 angle of the orbit, and then backwards and outwards to its insertion on 

 the eyeball. 



