. Fishes. Fishes. 354 The Grayling and the Smelt oceanic depths. The "Bombay duck" of the fishermen of India is a species of Harpodon, H. nehereus, with large mouth and arrow-shaped teeth. The dried fish is used as a reHsh. The BenthosauridcB are deep-sea fishes of similar type, but with distinct maxillaries. The BathypteroidcE, of the deep seas, resemble Aulopus, but have the upper and lower pectoral rays filiform, developed as organs of touch in the depths in which the small eyes become practically useless. Ipnopidffi.—In the IpnopidcB the head is depressed above and .the two eyes
. Fishes. Fishes. 354 The Grayling and the Smelt oceanic depths. The "Bombay duck" of the fishermen of India is a species of Harpodon, H. nehereus, with large mouth and arrow-shaped teeth. The dried fish is used as a reHsh. The BenthosauridcB are deep-sea fishes of similar type, but with distinct maxillaries. The BathypteroidcE, of the deep seas, resemble Aulopus, but have the upper and lower pectoral rays filiform, developed as organs of touch in the depths in which the small eyes become practically useless. Ipnopidffi.—In the IpnopidcB the head is depressed above and .the two eyes are flattened and widened so as to occupy most of its upper surface. These structures were at first sup- posed to be luminous organs, but Professor Moseley has thought them to be eyes. "They show a fiattened cornea extending along the median line of the snout, with a large retina com- posed of peculiar rods which form a complicated apparatus. Fig. 259.—Ipnops murrayi Giinther. destined undoubtedly to produce an image and to receive especial luminous ; The single species, Ipnops murrayi, is black in color and found at the depth of 2^ miles in various seas. The existence of well-developed eyes among fishes des- tined to live in the dark abysses of the ocean seems at first con- tradictory, but we must remember that these singular forms are descendants of immigrants from the shore and from the surface. "In some cases the eyes have not been specially modified, but in others there have been modifications of a lumi- nous mucous membrane leading on the one hand to phosphor- escent organs more or less specialized, or on the other to such remarkable structures as the eyes of Ipnops, intermediate between true eyes and phosphorescent plates. In fishes which cannot see, and which retain for their guidance only the general sensibility of the integuments and the lateral line, these parts soon acquire a very great delicacy. The same is the case with. Please note that th
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