Bathybius, the name given by Prof. Huxley to a very low form of the protozoa, found penetrating in every direction the viscid calcareous mud brought up in sea dredgings, by Drs. W. B. Carpenter and Wyville Thompson, from a depth of about 650 fathoms in the north Atlantic ocean. According to Huxley, a very large extent of the bed of the Atlantic ocean is covered by this living expanse of transparent gelatinous or protoplasmic matter, growing at the expense of inorganic elements, in which are imbedded granular bodies which he calls coccoliths and coccospheres, and to which they bear the same relation as the spicules of sponges do to the soft parts of these animals. This mud also contains minute foraminifera, the so-called globegerinm whose calcareous remains are forming a stratum at the bottom of the ocean, considered by Huxley the same in character and mode of formation as the chalk of the cretaceous period. Dr. Wallich, on the contrary, regards the so-called bathybius, not as an animal, but as a complex mass of slime, with many foreign bodies and the remains of once living organisms in it, and also with numerous living forms.
Denying the organic nature of bathybius, he maintains that the coccoliths and coccospheres stand in no direct relation to it, but are independent structures derived from preexisting similar forms, and that their nutrition is effected by a vital act which enables these organisms to extract from the surrounding medium the elements necessary for their growth. Dr. C. W. Gumbel has recently (1872) published a paper confirming the conclusions of Huxley, Carpenter, and Hackel with regard to the organic nature of the protoplasmic bathybius and the coccoliths (discoliths and cya-tholiths), and their relationship to each other. A similar growth in fresh water has been called pelobius.