The Scopelidæ are represented by some very extraordinary types. The genus _Bathypterois_, for example, occurring in depths ranging from 500 to 2,500 fathoms, is characterised by the development of enormously long pectoral fins to serve probably as organs of touch. ‘The rays of the pectoral fin,’ says Dr. Günther, ‘are much elongated. The ventral fins abdominal, with the outer rays prolonged, eight-rayed.... Gill rakers long.’ They are further characterised by the absence of any true phosphorescent organs and the smallness of their eyes. There can be little doubt, I think, that in these fishes the sense of touch or taste to a great extent takes the place of the sense of sight in other Scopelids. Not being provided with well-developed eyes or phosphorescent organs to attract their prey, the pectoral fins and the outer rays of the pelvic fins have become elongated and provided with special sense organs for searching for their food in the fine mud of the floor of the ocean. These long pectoral rays must have a very curious appearance in the living fish. Mr. Murray observes: ‘When taken from the trawl they were always dead, and the long pectoral rays were erected like an arch over the head, requiring considerable pressure to make them lie along the side of the body; when erected they resembled the Pennatulids like Umbellula.’ Filhol considers that when the fish is progressing through the obscurity of the abyss it probably carries these organs directed forward, seeking with them in the mud for any worms or other animals upon which it preys, or receiving through them warning of the approach of an enemy from whom it is necessary to make an immediate escape. One of the most remarkable of the deep-sea fish is closely related to Bathypterois, namely _Ipnops Murrayi_, living in depths of over 1,000 fathoms. It is about five inches long, of a yellowish brown colour, with an elongated subcylindrical body covered with large thin deciduous scales. There are no phosphorescent organs of the ordinary type met with in the Scopelidæ, but upon the upper surface of the head there is found a pair of organs somewhat resembling the ordinary eyes of fishes but devoid of retina and optic nerve, that, from the researches of Moseley, seem to be undoubtedly organs for emitting light. ‘The organs are paired expanses, completely symmetrical in outline, placed on either side of the median line of the upper flattened surface of the head of the fish, extending from a line a little posterior to the nasal capsules nearly to a point above the posterior extremity of the cranial cavity.’ They are covered by the upper walls of the skull, which is extremely thin and completely transparent in the region lying over them. ‘They are membranous structures 0·4 mm. in thickness marked by hexagonal areas about 0·04 mm. in diameter. When their surface is viewed by reflected light the appearance is that of a number of glistening white isolated