164 GEORGE L. STREETER 



section also passes through the anterior canal just oral to the 

 crus commune and through the vestibular pouch. The latter is 

 much reduced in size. It possesses a macula with a diminutive 

 nerve and ganglion, but the lagena is absent. The lateral canal 

 exists as a lateral pouch projecting from the vestibule (fig. 22). 

 In spite of the abnormal shape due to the deficient vestibule the 

 planes of the anterior and posterior canals intersect at the usual 

 angle. 



Labyrinth XII: (figures 23 and 21^). The photograph shown 

 in figure 23 is taken from Series X 7 C, slide 2, row 3, section 8. 

 The section passes through the endolymphatic sac, the crus 

 commune, the vestibule with the large pouch extending laterally 

 from it and representing the lateral canal. The endolymphatic 

 sac bears the usual relation to the chorioidal membrane. The 

 anterior and posterior canals are fairly normal. The vestibule is 

 enlarged and irregular, and illustrates the dropsical type. It 

 possesses the usual macula with nerve and ganglion (fig. 23). 

 The lagena is absent. 



Labyrinth XIII: {figures 25 and 26). The photograph shown 

 in figure 25 is taken from Series X 4 C, slide 1, row 3, section 5. It 

 passes through the crus commune, the vestibule with its thickened 

 floor, and through the lateral canal just being pinched off from 

 the vestibule. Slightly oral to this the separation becomes com- 

 plete. On examination of the reconstruction of this labyrinth 

 (fig. 26) it can be seen that the chief injury involves the dorsal 

 part of the labyrinth, and as a result the whole labyrinth is under- 

 sized. The greatest defect is in the posterior canal, which is 

 represented by a bud extending caudally from the crus commune. 

 A similar one is seen in figure 28 and the same kind of defect in an 

 anterior canal has already been seen in figure 20. The crus 

 commune and the anterior canal are small though complete. The 

 involvment of the median surface is shown by the absence of the 

 endolymphatic appendage and the lagena. 



Labyrinth XIV: {figures 27 and 28). The photograph shown 

 in figure 27 is taken from Series X 6, shde 1, row 4, section 2. 

 This labyrinth is of the dropsical or vesicular type. It is possi- 

 ble to recognize its general position but aside from the fairly 



