In Plate XVIII., Fig. 4, is shown a large light-giver,--the _Plagiodus_, a fish six feet in length. According to Dr. Günther, it emits light from various parts of its surface; the tips of the fins gleaming with a soft phosphorescence similar to that of the large-eyed _Beryx_ (Fig. 1) of same plate. The latter attains a length of about twenty inches. Quite as ferocious in appearance as the _Stomias_ is _Chauliodus_ (Plate XXI., Fig. 4), with long, lance-like teeth, gleaming fins, and a row of small phosphorescent plates that perhaps sparkle like so many gems as their bearer sails along in the greater depths. Exaggerations are often termed “fish-stories,” for the reason perhaps that improbable tales are related concerning the denizens of the sea by fun-loving mariners; but the most remarkable stories that the vivid imagination of those who go down to the sea in ships has ever devised are not as remarkable as the simple truths regarding the every-day history of fish-life. What can be more astonishing than the fact that these delicate forms are enabled to live in water where the pressure is so great that hard wood is crushed and glass reduced to powder? If a decade or so ago a statement had appeared in the daily press, to the effect that a fish had been discovered which could swallow another five times its own bulk, it would in all probability have been classed as a “fish-story,”--too big an one, indeed, to have even the merit of comical exaggeration: yet such a fish does exist in the black swallower, or _Chiasmodus_ (Plate XVIII., Fig. 5); the fish, besides being luminous, possessing this extraordinary faculty. The jaws, by a special arrangement, are capable of great extension; so that the fish actually draws itself over its prey, that may be many times its own bulk. The skin of the swallower seems to possess a rubber-like character, stretching to enormous dimensions, and often, when filled with gas, carrying the glutinous light-bearer into the upper regions of the ocean.