AUDITORY ORGAN. 207 



RELATION OF THE AUDITORY ORGAN TO THE AIR-BLADDER IN FISHES. 



A relation between the auditory organ and air-bladder is observable in four 

 families of Toleosteans (Siluroidei, Cyprinoidei, Characini, and Gymnoti). The 

 apparatus is formed on the same plan in all these Fishes. 1 



A chain of bones extends between the anterior end of the air-bladder and 

 the auditory organ, by means of which the relative fulness of the air-bladder 

 can be appreciated by the Fish. This chain arises by the metamorphosis of 

 certain parts of the four anterior vertebrae (upper arches and spines and 

 transverse processes), and four segments may be distinguished. In many cases 

 processes of the air-bladder are produced outwards to the side-walls of the body, 

 where the skin becomes very thin, forming a sort of tympanic membrane. 



(For further details, such as the relation of the whole apparatus to the 

 saccus endolymphaticus, the reader is referred to Wiedersheim's Lelirbuch rfer 

 vergl. Analomie.) 



BIBLIOGRAPHY. 



HADDON, A. C. On the. Stridulating Apparatus of Callomystax gagala. Jo-urn, of 



Anat. and Physiol. Vol. XV. 

 HASSK, C. The numerous Papers of this Author, which refer to all the chief 



Vertebrate groups, are published partly iu the Zeitsch. f. wiss. Zool. (Bd. XVII. 



und XVIII.), and partly in " Anatomischen Studicn." Leipzig, 1870-1873. 

 HENSEN, V. Physiologic dcs Gehb'rs. In the Handbuch dcr Physiologic by L. 



Hermann. Abthl. Sinncsorga-nc 2. Leipzig, 1880. 

 His, W. Anatomic mcnsch. Embryonal. Leipzig, 1880-1885. 

 HOWES, G. B. On the Presence of a Tympanum in the Genus Raia. Joicrn. of A /nil. 



and Physiol. Vol. XVII., 1883. 

 KUHN. See the works of this Author on the auditory organ of Fishes, Amphibia, 



and Reptiles in the Arch.f. mikr. Anat. Bd. XIV., XVII., XX. 

 MOLPEXHAUER, "VV. Die Rnticicklunrj dcs mittlcrcn und ausscrcn Ohres. Morph. 



Jahrb. Bd. 111., 1878. 

 PARKER, T. J. On the Connection of the Air-Bladder and the Auditory Organ in the 



tied Cod (Lotclla bacchus). Trans. N. Z. Institute, 1883. 

 RETZIUS, G. Das Gfehororgan dcr irirbclthicrc. I. Das Gclidrorgan dcr Fische imd 



Amphibicn. Stockholm, 1881. //. Das Gchororgan dcr lit-ptilun, dcr Voijd, 



imd dcr Sdugethicrc. Stockholm, 1884. 



"\VKBER, E. H. DC aure ct auditti Jtominis et animalium. Lipsiae, 1820. 

 AViEDERSHEiM, R.- Zur Anatwnic und Physiologic dcs Phyllodactylus curopaius, Ac. 



M.n-ph. Jahrb. Bd. I., 1876. 



1 T. J. Parker has also described a connection between the auditory organ, air- 

 bladder, and skin in the Red Cod (Lotella bacchus). 



