Plate XLVTII 



Inner and Middle Ear of Propifhccus diaflcnia, for Comparison with the Corresponding Parts in Notharcfus. After Milne 



Edwards 



1. Vertical anteroposterior section of the left bulla, mastoid and attic, seen from the medial side. Showing the malleus (m) and 

 incus (e), the tympanum (/) and tympanic annulus (c). Tlie chorda tympani is seen passing between the malleus and the incus. Four 

 times natural size. 



2. Vertical section (medial to the last) of the left bulla and periotic, lateral aspect. Showing the auditory prominence (ro), the 

 fenestra rotunda (seu cochleae, a), the malleus (m), incus (e), and outer part of the stapes {et); behind the incus is the large subarcuate 

 fossa (st) while above is another large sinus (st) which, as shown in an American Museum specimen (No. 31255), is merely a dorsal pro- 

 longation of the tympanic attic or recessus eintyinpanifus. In Notharcliis oshnr>il (Amer. Mus. No. 12659) the fossa subarcuata was 

 smaller and the epitympanic recess did not extcml dorsad in front of it. 



3. Vertical anteroposterior section of the inner ear of the right side, viewed from the encephalic side. Three times natural size. 

 Showing the expanded fossa subarcuata (/), the superior (.s), external is"), and posterior semicircular canals, the fenestra ovalis with 

 the foot plate of the stapes (o), the fenestra rotunda (r), the cochlea (I) and the cavum bullae or hypotympanic sinus of the bulla (6). 



4. Vertical transverse section of the right periotic, viewed from in front, passing through the middle of the fossa subarcuata (/), 

 the vestibule and internal auditory meatus (a). Three times natural size. Showing sinus lateralis (si), superior semicircular canal 

 (s), bottom of the subarcuate fossa (/'), surrounded by the posterior semicircular canal; .s' external semicircular canal, so, .so" openings 

 of the semicircular canals into the vestibule. 



5. Horizontal section of the left auditory bulla viewed from below. Three times natural size. Showing the auditory prominence 

 or cochlea (I), the carotid canal (tc), the tympanic annulus (c'), the Eustachian tube [ie), and the foramen lacerum posterius (Id). 



6. Left malleus (/«) and incus (e), mesal aspect. Eight times natural size. 



7. Left malleus, lateral aspect. Eight times natural size. 

 7a. The same, viewed from in front. 



8. Left incus, lateral aspect. Eight times natural size. 



9. Stapes (et) surmounted by os lenticulare (te) in situ in the fenestra ovalis and traversed by the osseous canal for the stapedial 

 artery (ti). 



10. Stapes (et) and lenticulare (le). Eight times natural size. 



11. Foot plate of stapes. 



