POSTURE OF MEMBRANOUS LABYRINTH 167 



rior canals are only represented by pouches opening out of the ves- 

 tibule in common with the cms commune. The shape of the 

 pouches is relatively normal, and they are only deficient in not 

 being pinched off from the vestibule. The lagena is quite normal. 

 The acoustic nerve and ganglion are diminutive. 



Labyrinth XVII: {figures 33 and 34). The photograph shown 

 in figure 33 is taken from Series X 3 A, slide 2, row 3, section 13. 

 Due to some mechanical or other injury the last three laby- 

 rinths in our series are quite imperfect, and from examination 

 of the sections alone (figs. 33, 35 and 37) one would be quite 

 unable to orient them. The reconstructions are of great assis- 

 tance in this respect. The section taken from Labyrinth XVII 

 was selected because it shows the labyrinth fragment' which 

 evidently was a portion of the main vesicle that became detached 

 and developed as a separate little sac (fig. 34, x). In figure 33 

 it can be seen outside the cartilaginous capsule, partially covered 

 by a cartilaginous coat of its own. It is not connected either by 

 nerve or duct with the main labyrinth. It is possible that in the 

 course of the operation a fragmeiit from the native vesicle was 

 left in the operation-pocket, and eventually formed this structure. 

 Examination of the reconstruction shows that there is an inter- 

 ruption in the lateral canal, its two ends being sealed off. One 

 never finds an open end in these imperfect labyrinths, they are 

 always sealed off. The anterior canal is small but well formed. 

 The posterior canal with the crus commune from a common 

 pouch communicating with the vestibule. The vestibule has a 

 normal macula with diminutive nerve and ganglion. There is 

 no lagena and no endolymphatic appendage. 



Labijrinth XVIII: (figures 35 and 36). The photograph shown 

 in figure 35 was taken from Series X 3 B, slide 2, row 1, section 11. 

 The whole oral region through which this section passes is of the 

 dropsical type. The caudal region is not so pathological. The 

 posterior canal, though incompletely separated from the vestibule 

 and the crus commune, is otherwise well formed. The caudal 

 half of the lateral canal is fairly normal, but the oral portion is 

 distended like the rest of this portion of the labyrinth. Ventrally 

 in one region this large labyrinth bulges through the parabasal 



