434 SCHULTE, SET WHALE. 



portion to reach the dorsum of the hyoid. In consequence the faucial surface of the velum does 

 not form a simple plane, but conforms to the direction of the canal. It is at first nearly hori- 

 zontal, it then slopes caudad and ventrad, and finally becomes horizontal again and, forming the 

 crescentic fold described above, projects into the pharynx as a horizontal shelf. Its dorsal 

 surface has a corresponding relief, with this difference, that at the junction of the first hori- 

 zontal plane with the sloping portion a prominent transverse ridge is formed. This ridge cor- 

 responds to the caudal border of the tensor palati, though it is rendered more prominent by a 

 diminution in the thickness of the mucosa behind it. From the ridge rostrad the velum forms 

 a continuation of the floor of the nasal fossa continuing the plane of the palate. Caudal to the 

 ridge the dorsum of the velum is deeply concave, forming a shallow bay or sinus, which extends 

 distad to the shelf-like margin of the velum. Laterad the sinus involves the wall of the pharynx 

 and attains considerable depth above the arcus palato-pharyngeus. In Carte and MacAlister's 

 plate vi, fig. 6, the sjnus and its limiting folds is tolerably well shown, and the probe, I believe, 

 passes through its fundus to enter the mouth. 



In the muscular wall of the pharynx Turner 1 found "at least two pairs of constrictors" 

 arising from the hyoid and thyroid, nor could I find evidence of the presence of the superior, 

 the internal pterygoid serving only to attach the very strong fibrous tissue of the pharynx, but 

 giving it apparently no muscular fasciculi, nor could I find any of lingual origin. The inferior 

 constrictor arises from the whole lateral or dorsal margin of the thyroid cartilage including its 

 posterior cornu, and is inserted into the dorsal raphe of the pharynx. The rostral fasciculi were 

 transverse and not clearly to be distinguished from those of the middle constrictor, so that the 

 two muscles appeared to blend rather than overlie one another. This blending was due to a 

 fibrous arch passing from the middle to the inferior constrictor, dorsal to the entrance between 

 them of the glossopharyngeal nerve and stylopharyngeus muscle, and the fasciculi arising from 

 this arch effectually closed the gap between the constrictors. The most caudal fasciculi from 

 the posterior cornu have a very oblique course, ascending to their insertion. In their course 

 they are nearly independent of the rest of the muscle and overlie the fasciculi from the base 

 of the cornu. These fasciculi from the two sides make a V open caudad, at the apex of which 

 the oesophagus emerges. As the origin of this muscle is much larger than its insertion, it is 

 necessary that it become condensed on the dorsum of the pharynx, and this is secured by the 

 ascent of its caudal fasciculi. The middle constrictor arises from the hyoid bar close to the 

 cranium and thence radiates to the dorsum and side of the pharynx. Its most rostral fasciculi 

 terminate with a very definite edge upon the pharyngeal aponeurosis at some distance from 

 the pterygoid. The pharynx has a maximum length from the hard palate to the beginning of 

 the oesophagus, of 32 mm. The greatest breadth of its lumen, just rostrad of the hyoid bars, 

 is 13 mm.; its greatest dorso-ventral height, 12 mm. 



(Esophagus. From its emergence between the oblique portions of the inferior constrictors 

 to its termination in the first stomach, the oesophagus has a length of 67 mm., of which 10 mm. 

 belong to its abdominal segment. In the neck and mediastinum to the point where the aorta 

 gains its left side, it is engaged between the hypaxial muscles and the trachea, and is dorso- 

 ventrally flattened to such a degree that its lumen is reduced to a transverse slit with its walls 

 in contact. Its greatest breadth is 4.5 mm. Where it is in contact with the aorta on the left 



1 (>i>. cit., p. 224. Sec also to the same effect Carte and MacAlister, op. tit., p. 2 ir>. 



