34 FOSSIL FISHES. 



The Xipliiidce or " Sword-fishes," are pelagic fishes inhabiting the 

 open seas ; they attain a length of from 12 to 15 feet. 



The upper jaw in these fishes is produced into a long cuneiform 

 weapon ; and the dorsal fin is enormously developed in the Flying 

 Sword-fish, Histioplwrus. 



The Sword-fishes are an ancient type of fishes, Tetrapterus having 

 been found in the Chalk of Lewes and Maestricht, and in the 

 London Clay of Sheppey, with Coelorhynclms. 



The Trichiuridce — " Scabbard-fishes," " Hair-tails," — include 

 those fishes with elongate compressed or band-like bodies ; wide 

 mouths armed with several strong teeth in the jaws or upon the 

 palate; the dorsal fin is long and many-rayed; the caudal fin is 

 forked. 



There are two extinct genera known, namely, JEncJiodzcs, from the 

 G-ault of Folkestone, the Chalk of England, and of Maestricht in 

 Holland; and AnencJielum, from the black (Eocene) slates of the 

 Canton Glaris. 



Another Eocene genus is Xip)hopterus ; whilst Lepidopus, Hemi- 

 thyr sites, and Trichiurichtliys, have been obtained in the Miocene 

 deposits of Licata in Sicily. 



The Palceorhynchidce were slender compressed fishes, having the 

 jaws prolonged into a sharp-pointed edentulous beak (like the bill 

 of a heron or crane); the dorsal fin extends from the nape of the 

 neck to the tail-fin, and the rays supporting it were not articulated. 

 They are supposed to have been deep-sea fishes. 



This family has no living representatives, and contains only two 

 extinct genera, namely, Palaorhynchus, from the Eocene Tertiary 

 of the Canton Glaris, and HemivUynclius, from the Paris Basin. 



The Acronuridce ("Surgeons") are represented by two extinct 

 species belonging to the genera Acanthurus and Naseus, found fossil 

 in the Eocene of Monte Bolca. 



Their living representatives at the present day are inhabitants of 

 tropical seas, and frequent Coral-Reefs, where they feed upon 

 vegetable substances, or upon the animal matter of the Coral. 



The Carangidce (''Horse-Mackerel," "Pilot-fish," "Boar-fish") 

 appear first in the Cretaceous formation, being represented by the 

 genera Plata.v, Vomer, and Aipiclithys, from the Chalk of Comen 

 in Istria (Trieste). 



They occur more numerously in the various Tertiary formations, 

 especially at Monte Bolca, where several still-existing genera 

 occur, as Zand us, Platax, Garanx {Carangopsis), Argyriosus> 

 (Vomer), LicJu'a, and Trachynotus. 



The extinct genera are Amplixstium, Ductor, and Semiophorus r 

 from Monte Bolca ; Arcliceus, from the dark (Eocene) slates of 

 Canton Glaris ; Pseudovomer and Equula, from the Miocene marls 

 of Licata in Sicily. 



Semiophorus is characterized by the enormous development of the 

 dorsal fin, which commences immediately above the head ; the 

 ventrals are long and slender, they are thoracic, and placed below 



