42 AYERS. [Vol. VI. 



is completely separated from the basilar papilla, and lies entirely 

 below and beyond it in the cochlear canal. It covers more than 

 a zone of the floor of the lagena, and reaches up on the side 

 walls of the chamber. The outer {i.e. anterior) end even passes 

 over on to the roof of the pocket. 



In structure the papilla lagenae resembles the macula sacculi. 



MhmLs polyglottiLS. 



The sense organ of the lagena forms a somewhat horseshoe- 

 shaped structure, which occupies the central part of the floor of 

 the lagena. Its boundaries are rendered conspicuous by the 

 presence of a sharply defined, white otolithic mass which ad- 

 heres to the tips of the long hairs of the sensory cells. The 

 rest of the floor is covered by a single-layered epithelium com- 

 posed of regular polygonal cells. The papilla lagenae has its 

 long axis transverse to the vertical (primary) axis of the lagena, 

 and is one and one-half times as long as the lagenar pocket is 

 broad. The sense organ consequently curves up on to the sides 

 of the pocket and reaches for a short distance on to the roof 

 portion of the pocket (not the membrana Reissneri). 



The histological characteristics of the sensory and supporting 

 cells of the sense organs are essentially the same as have been 

 already given for fishes. The cells connected with the nerve 

 fibres are quite uniformly flask-shaped and in general bear much 

 longer hairs than the authors have figured or described. 



According to Retzius, the auditory hairs are tolerably stiff, 

 straight, fibrillate, conical structures, which rise from a well- 

 defined cuticular plate as a base. This plate forms the cap of 

 the sensory cell. His measurements of the hairs gave lengths 

 varying between 0.048 and 0.005 mm. They end finely pointed, 

 the point being frequently turned to one side. Retzius leaves 

 the question of the nerve terminations in the sensory cells in 

 part an open question. He describes and figures one mode of 

 termination as certain. In preparations of the cristae acusticae 

 (maceration preparations) he found the thicker nerve fibres end- 

 ing in expanded plates in contact with the bases of the sensory 

 cells, and believes that the cell protoplasm here fuses with the 

 nerve axis cylinders. Other and finer fibres he found with unat- 

 tached ends between the cells some distance above their bases. 



My own studies lead me to look upon the nerve plates which 



