130 On the Digestive Organs of the 



of the tongue is the narrow elliptical aperture of the nares, b, of 

 which the slit, c, extends forwards nearly to its termination. At the 

 commencement of the slit behind, is, on each side, a transverse pa- 

 pillate flap, d, and another behind the aperture, e ; at its anterior 

 extremity is a soft prominence, from which proceeds forwards a soft 

 ridge, f. The tip or horny part is slightly, the lower mandible 

 deeply, concave. 



The tongue, Fig. 3, is 1 T 5 2 long, fleshy, rather narrow, concave 

 above; its sides nearly parallel, the tip, a, rounded and distinctly emar- 

 ginate, its free part beneath horny ; the lower surface of the sides 

 toward the base furnished with large mucous crypts ; the base, b, 

 concave in its outline, and fringed with pointed papillae directed 

 backwards. The space between the base of the tongue, b, and the 

 aperture of the glottis, c, is covered with mucous crypts, of which 

 there is also a lateral series on each side, d ; and the posterior part 

 of the pharynx is supplied with similar bodies irregularly disposed. 

 The aperture of the glottis, c, is defended behind by a number of 

 papillae, e, directed backwards, and arranged in two lateral lobes, 

 with a small intermediate one. 



Fig. 4 represents the intestinal canal in its natural position, view- 

 ed from before ; a b being the tongue, c d the trachea. The oesopha- 

 gus, e i, measured from the base of the tongue to the stomach is 13 

 inches long. At its commencement it has a diameter of 2, gradual- 

 ly contracts to \\ ; about the middle of the neck, or 4 inches from 

 the tongue, it dilates so as to form a kind of crop, f, capable of being 

 distended to a diameter of more than 3 inches, and lying rather to 

 the right side, the trachea, c d, passing along the left. On entering 

 the thorax at g, the oesophagus again contracts to about 1 inch, and 

 at its termination, i, enlarges to 1|, forming the proventriculus, h, 

 which is 1| long. 



At its upper part, the oesophagus has a slight outer layer of in- 

 conspicuous muscular fibres. It is encircled by transverse fibres, 

 forming a distinct coat. The inner or mucous coat is thrown into 

 longitudinal rugae when the organ is contracted ; otherwise it is 

 smooth and even. For a short space above the proventriculus, h, 

 there is a circle of distinct longitudinal fibres. Over the proventri- 

 culus itself, the fibres are all transverse ; and below it, at i, they are 

 more conspicuous. Between the muscular and mucous coats of the 

 proventriculus, are interposed numerous glandules, placed in appo- 

 sition, nearly at right angles to the surfaces of these coats. Fig. 5 

 represents a longitudinal section of the walls of the proventriculus, 

 of the natural size : a the outer or muscular coat, b the inner or mu- 



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