Fig. 90.—Young Sword-fish (Histiophorus), 14 mill. long. South Atlantic. (Magn.)
Fig. 91.—Young Sword-fish (Histiophorus), 60 mill. long. Mid-Atlantic.
Fig. 92.—Xiphias gladius, young, about 8 inches long.
The Plectognaths show no less extraordinary changes: an extraordinary form taken in the South Atlantic, and named Ostracion boops, is considered by Lütken to be the young of a Sun-fish (Orthagoriscus). In very young more advanced Sun-fishes (18 to 32 millimetres) the vertical diameter of the body exceeds, or is not much less than, the longitudinal; and small conical spines are scattered over its various parts. The caudal fin is developed long after the other vertical fins.
Fig. 93.—“Ostracion boops” (much magnified).
