In Opostomias micripnus, a dark black fish living at a depth of over 2,000 fathoms, there are two rows of ocellar organs running down the sides of the body from the head to the tail. In the living animal they are said to shine with a reddish lustre. In addition to these, the conspicuous organs, there are `groups` of fifty, a hundred, or even more very much smaller organs situated on the sides and back of the fish, each of which is lenticular in shape and consists of a number of short polygonal tubes containing a granular substance with rounded bases resting on the subjacent tissue. The whole organ is covered 79by a simple continuation of the cuticle of the body-wall. The granular substance contained in the tubes is most probably the seat of luminosity.