from The Century Dictionary and Cyclopedia
- n. In ichthyology, same as sphenotic and proötic.
Sorry, no etymologies found.
The Petrous Ganglion (ganglion petrosum; inferior ganglion) is larger than the superior and is situated in a depression in the lower border of the petrous portion of the temporal bone.
This membrane is stretched over a cavity in the bone, called the os petrosum, which cavity is called the tympanum, or drum of the ear, which is of a rounded figure, divided in its middle by a promontory, and continued backwards to the cells of the mastoid bone.
a round cavity in a hard part of the os petrosum; secondly, the semicircular canals, so called from their shape, which however is not exactly semicircular; thirdly, the cochlea, which is a beautifully convoluted canal, like the shell of a snail.