. An introduction to the osteology of the mammalia . ni is removed) the oppo-site wall of the bulla can be seen; or if a probe is passedinto the meatus, no obstacle will prevent its touching theinner wall. In the Tiger, which may be taken as a type of the Felida,the auditory bulla is very prominent, rounded and smoothon the surface, rather longer from before backwards thantransversely, its greatest prominence being rather to the 1 Especially developed in the Weasels (Muste!a\ in which also theentire parieties of the bulla are thickened and carcellous. i yo THE SKULL. [CHAP. inner side of the c
. An introduction to the osteology of the mammalia . ni is removed) the oppo-site wall of the bulla can be seen; or if a probe is passedinto the meatus, no obstacle will prevent its touching theinner wall. In the Tiger, which may be taken as a type of the Felida,the auditory bulla is very prominent, rounded and smoothon the surface, rather longer from before backwards thantransversely, its greatest prominence being rather to the 1 Especially developed in the Weasels (Muste!a\ in which also theentire parieties of the bulla are thickened and carcellous. i yo THE SKULL. [CHAP. inner side of the centre. The lower lip of the externalauditory meatus is extremely short; the meatus , in fact,looks like a large hole opening directly into the side of thebulla, On looking into this hole, at a very short distance(just beyond the tympanic ring), a wall of bone is seen quiteimpeding the view, or the passage of any instrument, intothe greater part of the bulla. In the section (Fig. 57) it willbe seen that this wall is a septum (s\ which rises from the. 00 FIG. 57.—Section of the left auditory bulla of the Tiger (Fells tigris). Sq squa-mosal ; Pt periotic ; BO basioccipital ; am external auditory meatus ; oc the outerchamber ; ic the inner chamber ; j the septum ; * the aperture of communicationbetween the chambers. (From Proc. Zool. Soc. 1869.) floor of the bulla along its outer side, and divides it almostcompletely into two distinct chambers ; one (pc), outer andanterior, is the true tympanic chamber, and contains thetympanic membrane and ossicula, and has at its anteriorextremity the opening of the Eustachian tube (e); while theother (ic), internal and posterior, is a simple but muchlarger cavity, having no aperture except a long but verynarrow fissure (*) left between the hinder part of the top of x.] CARNIVORA. 171 the septum and the promontory of the periotic, whichfissure expands posteriorly, or rather at its outer end, into atriangular space, placed just over the fenestra
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbones, bookyear1885
