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MR. J. W. CLARK ON THE VISCERAL 



[Feb. 20, 



to the same parts in the Porpoise, but gives no description of them. 

 I have drawn the parts in figs. 1 and 2. Fig. 1 represents the back 

 of the tongue with the opening of the larynx, when removed from 

 the mouth and suspended by the tongue ; fig. 2, the same parts 

 viewed from the right side. 



The root of the tongue is smooth, thick, and very much arched. 

 Between it and the origin of the epiglottis is a space measuring 1|" 

 in the centre, and 3" at the sides, from A to B. This space is con- 

 Fig. 2. 



Tongue, larynx, and trachea of Hippopotamus, viewed from the right side. 

 A. Root of tongue. B. Epiglottis. C. Arytenoid cartilages. 



cave, with a slight ridge in the middle, and furrows to the right and 

 left leading from the sides of the tongue to those of the epiglottis. 

 Between the epiglottis and the wall of the pharynx this channel is 

 very deep and narrow, but capable apparently of considerable dila- 

 tation. The epiglottis and arytenoid cartilages combine together to 

 form an elongated tubular structure that resembles in a very striking 

 manner the arrangement of these parts in the Cetacea, and may, I 

 think, be put occasionally to the same use, namely to advance into 

 and close the posterior nares, so as to preserve a free passage for air 

 to the lungs while the mouth of the animal is under water. The epi- 

 glottis is f " high in front, with a slight depression in the middle. 

 It wraps round the arytenoid cartilages, which are |" high behind. 

 It will be seen from the figures that the right cartilage slightly 

 overlaps the left. The tissue that connects them is extremely loose, 

 so as either to allow of their firmly uniting, or of their separating 

 sufficiently to admit a structure between them, such as the septum 

 narium, should they be thrust forward into the nostrils. It will be 

 seen that the arytenoid cartilages are curled upon themselves at 

 their outer border within the laryngeal aperture. I find that the 

 aperture of the posterior nostrils will just admit the structure I have 

 attempted to describe. 



I regret that the animal was so young that the mammse were 

 scarcely developed, and the mammary gland not at all. It would 

 be interesting to examine whether, in an adult animal, the mammary 

 gland bears any resemblance to that of the Porpoise, where the milk 



