APPENDIX. 553 



little to the left side. After these canals emerge 

 from the bones near the external opening, they 

 become irregular, and have several sulci passing 

 out laterally, of irregular forms, with correspond- 

 ing eminences. The structure of these eminence* 

 is muscular and fatty, but less muscular than the 

 tongue of a quadruped. In the Porpoise there 

 are two sulci on each side: two large and two 

 small, with corresponding eminences of different 

 shapes, the larger ones being thrown into folds. 

 The Spermaceti Whale has the least of this st; 

 ture ; the external opening in it comes farther for- 

 wards towards the anterior part of the lu 

 is consequently longer than in others of this ordtr. 

 Near to its opening externally, it forms a large 

 sulcus, and on each side of this canal is a car- 

 tilage, which runs nearly its whole length. In 

 all that I have examined, this canal, forwards 

 from the bones, is entirely lined with a thick cu- 

 ticle of a dark colour. In those which have only 

 one external opening, it is transverse, as in the 

 Porpoise, Grampus, Bottle-nose, and Spermaceti 

 Whale, &c. where double, they are longitudinal, 

 as in the I'iked Whale, and the large Whalebone 

 Whale. These openings form a passage for the 

 air in respiration to and from the lungs; for it 

 would he impossible for these animals to breathe 

 air through the mouth : indeed I believe the hu- 

 man species alone breathe by the mouth, and in 

 them it is mostly from habit ; for in quadrupeds 

 the epiglottis conducts the air into the nose. In 

 the whole of this nibe the situation of the opening 



