MULLENIX: EIGHTH CRANIAL NERVE. 22% 
IV. General Anatomy and Histology of the Ear of Fundulus. 
The anatomy of the ear of Fundulus conforms in a general way to 
that of Perca fluviatalis and other teleosts, as described by Retzius 
(812) in his monograph on the vertebrate ear. | ‘l’he external separa- 
tion between utriculus and sacculus, however, is less marked than in 
any species figured by him. Internally these divisions have a common 
cavity, excepting at the anterior and posterior extremities, where the 
utriculus is distinct. Anterior to the membrane which separates the 
two divisions posteriorly there is a horizontal shelf, which projects into 
the lumen of the ear, as shown in Figure 7 (Plate 2), and extends 
anteriorly for a considerable distance. ‘This may be regarded as 
marking internally the boundary between uticulus and sacculus. 
The external anatomy of the ear is shown in Figures 1-3 (Plate 1), 
and sections are shown in Figures 5-10 (Plate 2). I have followed 
Retzius in nomenclature, excepting that for the semicircular canals I 
have used the terms employed by Wiedersheim (:07). 
The wall of the labyrinth is composed everywhere of an outer base- 
ment membrane, which is lined by an epithelial layer (Figs. 5-10, 
Plate 2). In non-sensory regions this inner layer is very thin, and in 
many Bielschowsky preparations it can scarcely be distinguished from 
the basement membrane. In material stained by Mallory’s (:05) 
triple stain for connective tissue, however, it is easy to distinguish 
the two layers; the basement membrane stains dark blue, and the 
epithelium takes a lighter color, is obviously cellular in character, and 
the nuclei of its cells are stained red. 
The topographical distribution of the sensory areas and the branch- 
ing of the eighth nerve for their supply agree in Fundulus with the 
account given by Retzius for other teleosts. In the sensory areas the 
epithelium is much thickened, being composed here of at least two 
layers of cells, the small basal cells, next to the basement membrane, 
and the large cylinder cells, which bear the sense hairs. . Max Schultze 
in 1858 described the sensory epithelium in the ear of fishes as com- 
posed of basal cells and cylinder cells, with numerous nuclei between 
them, surrounded by protoplasm and having prolongations upwards 
and downwards, the former passing between the cylinder cells, and the 
latter between the nuclei of the basal cells. These intermediate cells 
he called the Fadenzellen. In subsequent publications Schultze 
and others described similar elements in the auditory epithelium of 
higher vertebrates. 
