SENSE ORGANS OF AMIURUS. 375. 
are designated /apillus, asteriscus and sagitta, are represented X six 
diameters in Figs. 18, 17, 16, Pl. IV. 
As will be seen from Fig. 11, Pl. I., the inferior parts of the 
labyrinth of both sides are nearest to each other where the ductus 
sacculo-utriculares open into them. In front and behind that plane 
they diverge from each other, but where they are nearest are con- 
nected by a short, thin-walled, transverse ductus endolymphaticus, 
which sends back a pyriform thin-walled saccus endolymphaticus (sinus 
impar) into the cavum sinus vmparis, but by no means filling up the: 
cavum. (Figs. 7 and 8, Pl. VI.) The horizontal section, Fig. 13, Pl. 
IV., passes through the ductus. I find no macula acustica in either 
ductus or sinus endolymphaticus, such as described by Nusbaum! and’ 
figured by him? for Cyprinus. The horizontal series from which Fig. 
13 is taken is quite perfect, and although the small macule acustice 
neglecte are easily enough detected, no trace of any thickened neuro- 
epithelinm exists in the parts referred to, nor does any branch of the 
cochlear nerve reach them. 
The mode of branching of the auditory nerve is indicated in Fig. 
10, Pl. I. It presents no difference from the scheme propounded by 
Retzius.* As already mentioned, the anterior division which, imme- 
diately after its origin, spreads itself out in a shell-like fashion, arises 
somewhat lower from the twbherculum acusticum than the posterior. 
It furnishes branches to the marula acustica recessus utriculi, crista 
acustica ampulle sagittalis, and crista acustica ampulle horizontalis. 
The cords of the posterior division may be separated nearly up to 
their origin ; of these the most anterior in origin and ventral in 
position is destined for the macula acustica sacculi, the next is for 
the papilla acustica lagence cochlee, and the highest and most pos- 
terior in origin, as well as the most dorsal in its backward course, is 
for the crista acustica ampulle frontalis. The latter slender cord, 
which furnishes a twig to the macule acustice neglecte, may be 
coalesced with the foregoing for some distance after leaving the 
brain. I have not noticed the macule neglecte in the fresh adult 
labyrinth, but they are very plain although of small size on opposite 
sides of the basal part of the utriculus in the horizontal series 
1Zool. Anzeiger IV., 552. 
2 Relations of the Auditory organ and Air-bladder in the Cyprinoids (Polish) Lemberg, 1883. 
T. IV., Fig. 19. 
8 Arch. Anat. Phys. 1880, p. 240. 
