184 



Charles Searing Mead. 



The two parts are separated externally by the fenestra vestibuli and 

 the fenestra cochleee (fenestras ovalis et rotunda), internally by the 

 foramen acusticiun, and dorsally by the foramen nervi facialis. The 

 median face of the pars cochlearis is flattened so that it conforms 



i.jAK ph. 71. c. 



Fig. 4. Section showing the notocbord n.c. beneath the basal plate and the 

 thin lamella of cartilage between the latter and the cochlear portion of the 

 ear. x l^- 



a.s.c, anterior semicirciilar canal ; Till, nervus aciisticus ; VII, portions of 

 nervus facialis; g.coch., ganglion cochleare; ch.tt)., chorda tynipani ; X, nervus 

 vagus; XII, nervus hypoglossus; ph.. pharynx; i.j.r., internal jugular vein; 

 hyo., cornu hyale ; tijm.c, tympanic cavity; coch., cochlea; f.ov., foramen 

 ovale; in., incus; st., stapes; sac, sacculus ; vtr., utriculus ; jja., anlagen of 

 parietal bone; f.l.p., fissura laminre parietalis ; l.j)ar., lamina parietalis. 



better to the inner snrface of the cranium, while the rest of its 

 surface is hemispherical in shape. Compared with Talpa, the pars 

 cochlearis is relatively bigger and the pars vestibularis relatively 

 smaller. In the latter form the cochlear portion occupies only about 



