392 



ANATOMY OF VERTEBRATES. 



there is a crico-pharyngeus, arising from the posterior and inferior 

 margin of the cricoid cartilage, whence its fibres extend obliquely 

 upwards along the sides of the pharynx. The homologue of the 

 stylo-pharyngeus is a cylindrical muscle, arising from the stylo- 

 hyal, and, running from behind forward upon the sides and upper 

 part of the pharynx, mixing its fibres with those of the superior 

 constrictor : its action is to raise the commencement of the 

 pharyngeal sac, which it at the same time dilates and draws back- 

 ward. There is likewise a small muscle derived from the 

 middle part of the stylo-hyal, the fibres of which run backward 

 and inward, so as to meet those of the muscle last mentioned. 

 Lastly, there are two other muscles, the fibres of which take a 

 longitudinal direction. One of these, the pharyngeus proprius, 

 arises from the tendinous middle line that extends from below 

 the insertion of the stylo-pharyngei, and is prolonged downward 

 along the posterior and lateral walls of the oesophagus: the 

 other, the aryteno-pharyngeus, is a small muscular band proceed- 

 ing from the back part of each arytenoid cartilage, and running 

 down the front of the oesophagus towards the stomach. 



The mouth of the Hog-tribe is served by the uprooting modi- 

 fication of the upper lip and nose, forming the 'snout.' The 

 palate is ridged. In the Babyroussa Yrolik l found a small pouch 

 at the back part of the commencement of the oesophagus : a pair 

 of air-sacs continued from the posterior nostrils communicate 

 with the back part of the pharynx. 



The mouth of the Ruminants is chiefly re- 

 markable for the callous pad covering the 

 edentulous borders of the premaxillaries, and 

 for the number of hard, commonly retroverted 

 papillae, developed from extensive tracts of the 

 buccal membrane : those on the inside of the 

 lower lip are large and pointed ; interspersed 

 with groups of mucous follicles. Along the 

 roof of the mouth they are flattened, and dis- 

 posed in parallel transverse rows with retro- 

 verted denticulate margins: the papillae usually 

 attain their greatest size inside the cheeks, 

 opposite the masticating line of the molars. 

 In the Camel they are aggregated and ob- 

 tuse, fig. 301. In the Giraffe they are close- 

 set, strong, retroverted, pointed, some of them half-an-inch in 

 length, and giving off secondary papillae. In the act of rumi- 



301 



Buccal papillas of theBactrian 

 Camel. 



cliv. p. 31, pi. iii. 



