Nasal Fassar/es of tlie Cachalot. 051 



from tlie marp;ins of the passap^cs in question. The con- 

 stricting muscles are by no means so obvious, since they 

 are seen as transversely-cut fibres lying between the former, 

 which in the same way are hardly massed into bundles, a 

 state of affairs which doubtless will be seen later in develop- 

 ment. The dilator nnscles extend throughout the whole 

 course of the nasal passages while they lie outside the bones 

 of the skull. They are less developed, however, in the later 

 sections. The muscles are particularly conspicuous for a 

 distance of nearly 4 mm. They are not only attached to 

 the margins of the blow-tubes, but to the cartilages associated 

 with these. I could see no striation in these fibres ■^. 



§ Nasal Pharynx. 



After the fusion of the two nasal canals into one, the 

 respiratory passage may be termed the pharynx — or, better, 

 perhaps, as it has been called, the naso-pharynx. This 

 region occupies altogether twenty slides of the series upon 

 which I have worked; and its length in millimetres will be, 

 therefore, as near as may be, 6*5. It is thus a triHe more 

 than half of the length of the double region of the nasal 

 passages which precedes it. Clearly, therefore, it is notable 

 for its length, when compared proportionately with other 

 mammals. It is also actually very long in relation to 

 whole head of the whale. 



For a considerable distance no particular change occurs 

 in the shape of the tube ; the two halves do not become 

 more intimately connected, and continue to lie at an angle 

 with each other — the two limbs representing the two 

 separate blow-hole passages joining below and diverging 

 above. Later the angle becomes greater and the whole 

 acquires a more flattened aspect from above downwards. 

 It is in this region that the Eustachian tube arises, which I 

 deal with later. Later still — at any rate, within '6 mm., — the 

 tube gets to have a triangular section, the flat side being 

 dorsal, and ridges appear which run longitudinally. Almost 

 dii-ectly the whole tube becomes much more elongated from 

 above downwards and narrow from side to side, and has a 

 series of ridges along both sides, appearing, of course, in the 

 sections as short ingrowths into the lumen. Later still it 

 again acquires a triangular form in section ; but this time 



♦ For the matter of that, I could find no striation of any of the 

 Tohmtary muscles of that region of the lody of this foetus ^vhich 1 have 

 hitherto studied, viz. the head. 



