SENSE ORGANS OF AMIURUS. 375 



are designated lapillus, asteriscus and sagitta, are represented X six 

 diameters in Figs. 18, 17, 16, PI. IY. 



As will be seen from, Fig. 11, PI. I., the inferior parts of the 

 labyrinth of both sides are nearest to each other where the ductus 

 saccxdo-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 imparis; but by no means filling up the 

 cavum. (Figs. 7 and 8, PL YI.) The horizontal section, Fig. 13, PI. 

 IY., passes through the ductus. I find no macula acustica in either 

 ductus or sinus endolymphaticus, such as described by Nusbaum 1 and 

 figured by him 2 for Cyprinus. The horizontal series from which Fig. 

 13 is taken is quite perfect, and although the small maculae acustica; 

 neglectce are easily enough detected, no trace of any thickened neuro- 

 epithelium 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. 

 1 0, PL I. It presents no difference from the scheme propounded by 

 Retzius. 3 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 tuberculum acusticum than the posterior. 

 It furnishes branches to the macula acustica recessus utriculi, crista 

 acustica ampulla; sagittalis, and crista acustica ampulla} 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 cochlea?, and the highest and most pos- 

 terior in origin, as well as the most dorsal in its backward course, is 

 for the crista acustica ampulla; frontalis. The latter slender cord, 

 which furnishes a twig to the macula; acustica; neglectm, may be 

 coalesced with the foregoing for some distance after leaving the 

 brain. I have not noticed the maculae neglectse 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 



JZool. Anzeiger IV., 552. 



' 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. 



