The Collaborative International Dictionary
Bathybius \Ba*thyb"i*us\, n. [NL., fr. Gr. baqy`s deep + bi`os life] (Zo["o]l.) A name given by Prof. Huxley to a gelatinous substance found in mud dredged from the Atlantic and preserved in alcohol. He supposed that it was free living protoplasm, covering a large part of the ocean bed. It is now known that the substance is of chemical, not of organic, origin.
Wiktionary
n. (context zoology obsolete English) A gelatinous substance found in mud dredged from the Atlantic and once supposed to be a free living protoplasm, later found to be the result of precipitation.
Usage examples of "bathybius".
About the same time bathybius, which at one time bade fair to supplant it upon the throne of popularity, died suddenly, as I am told, at Norwich, under circumstances which did not transpire, nor has its name, so far as I am aware, been ever again mentioned.
Our biologists therefore stifled bathybius, perhaps with justice, certainly with prudence, and left protoplasm to its fate.