No. I.] THE VERTEBRATE EAR. 37 



organ, which I shall call the Sauropsid organ, lies upon the inner 

 cartilage, and bears the same relation to the first named organ, 

 which I believe to be the incipient organ of Corti, that the large 

 epithelial ridge does to the small epithelial ridge in the develop- 

 ing mammalian ear. 



The hair cells are more widely separated in these two organs 

 of the Alligator than in the mammalian organ of Corti, and in 

 consequence the membrana tectoria is looser in texture, but 

 owing to the absence of otoliths and the strength and size of 

 the individual hairs, the membrane appears much simpler in 

 structure than that of the lagenar organ, for example. I have 

 positive proof that there is nothing in the Alligator's membrana 

 tectoria other than the long filaments into which it is with no 

 great difficulty resolved, and there can be no doubt that these 

 filaments are normally continuations of the auditory cells as 

 their proper hairs. 



Miniits polyglottits (PI. VI, Figs. 6 and 8). 



In the Mocking-bird the internal ear lies in the occipital face 

 of the skull. The anterior edge is presented outwards, the pos- 

 terior inwards, and the outer face looks downwards and almost 

 directly backwards. 



The anterior canals lie in planes nearly transverse to the long 

 axis of the body, instead of occupying positions very nearly 

 parallel to the sagittal plane. They are not, however, perpen- 

 dicular to the long axis. The posterior canals lie very close to 

 the edges of the foramen magnum ; in fact, may be said to take 

 part in forming its thickened border. Owing to the curvature 

 of the occipital face of the skull, the so-called horizontal canals 

 lie very nearly in the vertical plane and transverse to the long 

 axis of the body. 



The sense organs found in this type of ear are — 



1. Macula utriculi. 



2. Macula sacculi. 



3. 4. Cristas acusticse ampullarum (anterioris and horizontalis). 



5. Crista acustica ampullae posterioris. 



6. Crista acustica abortiva. 



7. Papilla acustica basilaris. 



8. Papilla acustica lagenae. 



