130 PROFESSOR OWEN ON THE ANATOMY OF 



they may be blended with the more alkaline and solvent salivary secretion of the paro- 

 tids after being pounded by the tongue against the callous ridges, before they are finally 

 swallowed : the singular backward extension of the fauces and nasal passages appears 

 to relate in part to the presence and function of this receptacle. 



The buccal cavity gradually contracts beyond the receptacle to the hyoid bone, 

 immediately in advance of which, nineteen inches from the aperture of the mouth, are 

 situated the tonsils (PI. XXXVIII. fig. 2,t,t; PI. XXXIX. fig. 3, t), each tonsil being 

 an oval patch of a thin layer of muco-glandular substance with a finely reticulate sur- 

 face, measuring one inch by nine lines. Behind the tonsils, and between them and the 

 basihyals, a pouch of the gular membrane {ih. s) descends between the epihyals ; it is 

 one inch and a half in depth, by one inch in width. 



One inch behind the prehyoid pouch, the extremity of the epiglottis, v (bisected 

 in fig. 2, PI. XXXVIII.), is seen projecting into the cavity of the mouth ; it is broad 

 and trilobed, the middle lobe subquadrate and curved downwards and backwards. A 

 hyo-epiglottideus muscle extends from the back of the basihyal to the fore part of the 

 base of the epiglottis : some fibres from this muscle appear to spread upon the prehyoid 

 pouch. 



The thyroid cartilage (PI. XXXVIII. fig. 1, 5) is ossified. The cricoid {ih. fig. 2, y) 

 is cartilaginous. The arytenoids {ib. fig. 2, w, w) are low obtuse cartilages. 



The chorda vocales (PI. XXXIX. fig. 3, x, x) extend from the middle of the lower and 

 front part of the thyroid forwards to the arytenoid cartilages, w, the fold containing 

 them expanding as they advance. There is a shallow fossa beneath this fold and a 

 deeper one above it, or between it and the folds continuing from the epiglottis, v, to 

 the arytenoids. There is a small fibrocartilage supporting an obtuse prominence from 

 near the hinder end of the epiglottidean fold. The posterior interspace of the first 

 tracheal cartilage is half an inch wide, but at the third ring the posterior extremities 

 come into contact. 



The posterior margin of the soft palate terminates by a low angular projection like 

 the rudiment of a uvula {ib. u) opposite the base of the epiglottis. From the sides of 

 this uvula the membrane arches backward, and gradually subsides upon the beginning 

 of the oesophagus. 



The whole length of the nasal passage (PI. XXXIX. fig. 3, c, e) is twenty-two inches. 

 The first inch is surrounded by the cartilagmous part of the nose : the next thirteen 

 inches is enclosed by bone : the last eight inches of the canal has musculo-membranous 

 walls, and is an enormously-developed homologue of the ' palatum molle' in Man. 



Constrictores pharyngis. — The canal of the posterior nares is continued far back be- 

 yond the base of the skull {ib. fig. 3, e, e), and the homologues of the 'constrictor 

 pharyngis' act upon this canal before they embrace the proper pharynx. They consist 

 of several distinct muscles. The most anterior one {ceratopharyngeus, PI. XXXIX. 

 fig. 2, /) comes off from an extent of more than an inch of the middle part of the cerato- 



