Note 40 — Chapter X · BY CRAB-LIGHT.

Page 77. Another species in which this change had taken place is Galathodes antonii, an allied form which is shown in the central figure of the frontispiece. Many more, as Willemœsea, Pentacheles, Polycheles, and others, have organs of vision, which have undergone more or less change. It has been suggested that certain deep-sea crabs, as Geryon tridens, Gonoplax, Donychus, and Munida, have phosphorescent eyes.

In Ptycogaster formosus (Plate XIII., Fig. 1), we find an interesting form, living at a depth of twenty-eight hundred and fifty feet, or more than half a mile, from the surface, which is provided with well-developed eyes.