_Mola mola_, the common head-fish or sunfish, is found occasionally in all tropical and temperate seas. Its form is almost circular, having been compared by Linnæus to a mill-wheel (mola), and its surface is covered with a rough, leathery skin. It swims very lazily at the surface of the water, its high dorsal often rising above the surface. It is rarely used as food, though not known to be poisonous. The largest example known to the writer was taken at Redondo Beach, California, by Mr. Thomas Shooter, of Los Angeles. This specimen was 8 feet 2 inches in length, and weighed 1200 pounds. Another, almost as large, was taken at San Diego, in April, 1904. No difference has been noticed among specimens from California, Cape Cod, Japan, and the Mediterranean. The young, however, differ considerably from the adult, as might be expected in a fish of such great size and extraordinary form. (See Figs. 109 and 110, Vol. I.) Fragments named _Chelonopsis_, and doubtfully referred to _Mola_, are found in the Pliocene of Belgium. Certain jaws of cretaceous age, attributed to _Mola_, probably belong, according to Woodward, to a turtle. [Illustration: FIG. 364.—The King of the Mackerel, _Ranzania makua_ Jenkins, from Honolulu. (After Jenkins.) ] In the genus _Ranzania_, the body is more elongate, twice as long as deep, but as in _Mola_, the body appears as if bitten off and then provided with a fringe of tail. The species are rarely taken. _Ranzania truncata_ is found in the Mediterranean and once at Madeira. _Ranzania makua_, known as the king of the mackerels about Hawaii, is beautifully colored brown and silvery. This species has been taken once in Japan. In Hawaii it is believed that all the Scombroid fishes are subject to the rule of the makua and that they will disappear if this fish be killed. By a similar superstition, _Regalecus glesne_ is "king of the herrings" in Norway and about Cape Flattery, _Trachypterus rex salmonorum_ is "king of the salmon." CHAPTER XXV PAREIOPLITÆ, OR MAILED-CHEEK FISHES =THE Mailed-cheek Fishes.=—The vast group of _Pareioplitæ_ (_Loricati_) or mailed-cheek fishes is characterized by the presence of a "bony stay" or backward-directed process from the third suborbital. This extends backward across the cheek toward the preopercle. In the most generalized forms this bony stay is small and hidden under the skin. In more specialized forms it grows larger, articulates with the preopercle, and becomes rough or spinous at its surface. Finally, it joins the other bones to form a coat of mail which covers the whole head. In degenerate forms it is again reduced in size, finally becoming insignificant.