Percomorphi 267 



from the lower Eocene near London. Several other tunny- 

 like fishes occur in the lower Tertiary. 



The Escolars : Gempylidae. More predaceous than the mack- 

 erels and tunnies are the pelagic mackerels, Gempylidce, known 

 as e scalar s ("scholars"), with the body almost band-shaped 

 and the teeth very large and sharp. Some of these, from 

 the ocean depths, are violet-black in color, those near the 

 surface being silvery. Escolar violaceus lives in the abysses 

 of the Gulf Stream. Ruvettus pretiosus, the black escolar, 

 lives in more moderate depths and is often taken in Cuba, 

 Madeira, Hawaii, and Japan. It is a very large fish, black, 

 with very rough scales. The flesh is white, soft, and full of 

 oil; sometimes rated very high, and at other times too rank 

 to be edible. The name escolar means scholar in Spanish, but 

 its root meaning, as applied to this fish, comes from a word 

 meaning to scour, in allusion to the very rough scales. 



Promethichthys prometheus, the rabbit-fish, or conejo, so- 

 called from its wariness, is caught in the same regions, being 

 especially common about Madeira and Hawaii. Gempylus 

 serpens, the snake-mackerel, is a still slenderer and more voracious 

 fish of the open seas. Thy r sites atun is the Australian "barra- 

 cuda," a valued food-fish, voracious and predaceous. 



Scabbard- and Cutlass-fishes : Lepidopidae and Trichiuridae. 

 The family of Lepidopidce, or scabbard-fishes, includes degen- 

 erate mackerels, band-shaped, with continuous dorsal fin, 

 and the long jaws armed with very small teeth. These are 

 found in the open sea, Lepidopus candatus being the most 

 common. This species reaches a length of five or six feet 

 and comes to different coasts occasionally to deposit its spawn. 

 It lives in warm water and is at once chilled by the least cold; 

 hence the name of frostfish occasionally applied to it. Several 

 species of Lepidopus are fossil in the later Tertiary. Lepido- 

 pus glarisianus occurs in the Swiss Oligocene, and with it 

 Thyrsitocephalus alpinus, which approaches more nearly to the 

 Gempylida. 



Still more degenerate are the Trichiuridce, or cutlass-fishes, 

 in which the caudal fin is wanting, the tail ending in a hair-like 

 filament. The species are bright silvery in color, very slender, 

 and very voracious, reaching a length of three to five feet. 



