File:Image from page 389 of "On the anatomy of vertebrates (electronic resource)" (1866) (14755250082).jpg

Identifier: b20416039_001 Title: On the anatomy of vertebrates [electronic resource] Year: 1866 (1860s) Authors: Owen, Richard, 1804-1892 Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds Publisher: London : Longmans, Green Contributing Library: Wellcome Library Digitizing Sponsor: Wellcome Library

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Text Appearing Before Image: fishes this communicates with the vestibuleby a narrow canal. All the parts of the labyrinth are of largesize; yet the compartments of the otocrane which the semicircularcanals, fig. 229, e, J) g, traverse, tf are much too wide for them,and they are supported in these passages by a very fine cellularmembrane.2 In the Pike (Esox lucins) a pyriform membranoussac, lodged in the commencement of the spinal canal, opens intothe vestibule near the entrance of the posterior semicircular canal. The Plectognaths, Lophobranchs, Holocephali, and Sturgeonsresemble the bony fishes in the form and position of the labyrinth;but the otolites are represented by cretaceous particles; and inthe Chimsera the communication between the cranium and otocranebegins to contract. The otolites are a hard chalky substance in 1 Figures of these bodies will be found in xx. vol. iii. pi. 35; in lxviil, lxxl, andin lxxil, with microscopic figures of the crystals. 2 Hunter, vu. iii. p. 101. 344 ANATOMY OF VERTEBRATES.

Text Appearing After Image: the Lepidosiren, in which, as well as in the Plagiostomes, thewhole labyrinth is buried in the thick basi-lateral walls of thecranium. In Plagiostomes the capsule conforms more closely insize and configuration to the membranous228 labyrinth; its passages and compartments are lined by a delicate perichondrium, fromwhich filaments are detached to supportthe semicircular canal. The vestibule isdivided in the Skate and Tope into threecompartments, — the i alveus communis,fig. 228, a ; the sac, ib. b, and the cysticule,ib. c ; and it has also a small cascal append-age, called the i utricule, ib. d: the otoliticcontents are like soft chalk, and are dis-posed in two masses ; one very laro;e, occu- Organ of hearing, Skate, lxviii. , , - • i i i pying the sac and the cysticule, the othersmall, and lodged in the utricule. A canal extends in Sharksfrom the vestibular capsule to a foramen at the upper part ofthe occiput, which is closed by the skin. In the Rays, besidesthis 4 fenestra capsula

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