Vaughn Thompson is opposed to the theory that the objects on the side of the trunk, and along the ventral face of the tail, of these little creatures are eyes. “A re-examination,” he says, “proves that they are not visual organs at all, but constitute rather a highly complicated luminous apparatus together; the lenticular body of the organs acting as a condenser, which, in connection with the great mobility of the globules, enables the animal to produce at will a very bright flash of light in a given direction. The great majority of species possess these organs, generally arranged in a perfectly similar manner; but in a large, deep-sea, non-pellucid _Euphausia_, V. Willemoes Suhm could not detect these globules in their usual place. [Illustration: PLATE XV. LUMINOUS CRUSTACEANS. _Nematocarcinus gracilipes._ _Cyclops_ (magnified).] “The phosphorescent light emitted by the species of the _Euphausiidæ_ was frequently under observation. One taken by forceps exhibited a pair of bright, phosphorescent spots directly behind the eyes; two other pairs were on the trunk, and four other spots were situated along the median line of the tail,--all quite visible to the naked eye. The light of these is a bluish white. After a brilliant flash has been emitted from the organs, they glow for some time with a dull light. The light is given out at will by the animal, and usually, but not always, when irritated. The most brilliant flashes occur when freshly taken from the sea. Under the microscope these phosphorescent organs appear as pale-red spots, with a central, clear, lenticular body. The light comes from the red pigment surrounding the lenticular space.” Mr. Murray observed at night, on the surface of the sea in the Faeroe Channel, large patches and long streaks of apparently milky-white water. The tow-nets caught in these immense numbers of _Nyctiphanes novejica_, and the peculiar appearance of the water seemed to be due to the diffused light emitted from the phosphorescent organs of this species. Many of the deep-sea shrimps are remarkable for their brilliant coloring. _Aristes_ is a bright red, with _antennæ_ five or six times as long as its body. Equally strange is the long-legged _Nematocarcinus_ (Plate XV., Fig. 1), and the _Oplophori_ and _Notostomi_, curious little creatures, that have no common names, are of an intense red hue, while others are brown, rose, or spotted with red; showing that Nature decorates her own even in the uttermost depths of the sea. CHAPTER XI. SEAS OF FLAME.