56 STUDIES IN COMPARATIVE ANATOMY. 



A number of pits in the mucous membrane of tlie floor and 

 sides of the pharynx are doubtless glandular. They are altogether 

 absent from the middle line, but become densely aggregated 

 towards the root of the tongue on the sides of the pharyngeal 

 floor. Similar glandular crypts line a pouch, in our example 

 about an inch deep and half an inch in diameter/ which lies on 

 each side in the lateral wall of the pharynx in front of the 

 transverse fold described above. In the lateral spaces behind 

 the transverse fold are other flattened glands. 



The thyro-hyals support the pharyngeal wall laterally, and 

 their expanded ends can be plainly felt upon its inner surface, in 

 the recess behind and within the lateral attachment of the velum. 

 Professor A. H. Garrod has remarked ^ that the basi- and thyro- 

 hyals form a lower arch quite distinct from the bifurcate stylo- 

 hyals, and he adds : " In the elephant, therefore, the deficiency 

 of the lateral intermediate elements of the hyoid apparatus per- 

 mits of a much greater movement of the base of the tongue than 

 in the ungulata, whose nearly rigid stylo-hyals, epi-hyals and 

 cerato-hyals can allow of little more than an antero-posterior 

 movement of the base of the tongue in part of the circle of which 

 the hyo-cranial attachment in the centre." 



(Esophagus. 



Dr Watson states that " the muscular fibres of the oesophagus 

 are distinctly striated even down to the oesophageal opening in 

 the diaphragm, and are arranged in two layers — an external, the 

 fibres of which are distinctly longitudinal in direction ; and an 

 internal, which consists of two sets of spiral fibres, one of which 

 passes from right to left, whilst the other passes in the opposite 

 direction, and thus gives rise to a decussation of the fibres at all 

 points." 



Like Dr Watson, we found no trace of a muscle connecting 

 the trachea with the oesophagus and stomach, such as was 

 described and figured by Dr Harrison of Dublin.^ 



- Mayer found this pouch to be 3^ inches long and I5 wide. 



* Froc. Zool. Soc. May 1875. 



'^ Froc. Foy. Irish Acad. vol. iv. p. 133 (1847). 



