Perilymph
Perilympha
Definition
The osseous labyrinth is lined by an exceedingly thin fibro-serous membrane; its attached surface is rough and fibrous, and closely adherent to the bone; its free surface is smooth and pale, covered with a layer of epithelium, and secretes a thin, limpid fluid, the perilymph that separates the osseous labyrinth from the membranous labyrinth.
References
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
