SÜB-CLASS VI TELEOSTEI 97 



median. Not certainly known below the Upper Eocene of Monte Bolca, near 

 Verona. Small species in the freshwater Lower Miocene of Unterkirchberg, 

 near Ulm, Würtemberg. 



Alosa, Engraulis, Ciiv. Tertiary and Recent. 



Meletta, Val. (Fig. 173). Small slender fishes with thick cycloid scales, 

 which are marked with three to six pairs of radiating grooves. Jaws tooth- 

 less. Ventral ridge scutes large. Tertiary and Recent. Very common in 

 the Lower Oligocene (Melettaschiefer) of the Carpathians, Croatia, Glarus, 

 Alsace, etc. 



Family 7. Salmonidae. Salmon. 



As Clupeidae, but a small adipose fin behind the dorsal fin. Upper Tertiary 

 and Recent. 



Fossil skeletons of the existing Mallotus viUosus, Müll., are very common in 

 nodules in Pleistocene Clay on the coast of Greenland and in the glacial 

 deposits of Canada. 



Family 8. Osteoglossidae. 



Head bones much ihickened, and cheek plates robust. Margin of upper jaw formed 

 both by premaxilla and maxilla. Scales large and thick, composed of mosaic-like 

 pieces. Upper Cretaceous to Recent. 



Phareodus, Leidy (Dapedoglossus, Cope). Laterally compressed deep-bodied 

 fishes from the Eocene Green River Shales of Wyoming, U.S.A. 



(?) Brychaetus, Ag. London Clay ; Sheppey. Plethodus, Dixon. Cre- 

 taceous ; England. Anogmius, Cope. Upper Cretaceous ; Kansas. 



Osteoglossum and other genera are large freshwater fishes living in the 

 tropics. 



Family 9. Halosauridae. Günther. 



Eel-shaped fishes with pectoral and pelvic fins, a short dorsal fin, an extended anal 

 fin usually confluent with the diminutive caudal, and both head and trunk covered with 

 cycloid scales. Margin of upper jaw formed both by premaxilla and maxilla. Verte- 

 bral centra as delicate cylinders. Lateral line ivith luminous organs along the ventral 

 border of the flank. Upper Cretaceous to Recent. 



Halosaurus, Johnson, living at great depths in the ocean. Echidnocephalus, 

 W. von der Marck, an almost identical genus from the Upper Cretaceous of 

 Sendenhorst, Westphalia. 



Family 10. Dercetidae. Smith Wood ward {Hoplopleuridae, Pictet p.p.). 



Eel-shaped fishes with pectoral and pelvic fins, a more or less extended dorsal fin, 

 and separate anal and caudal fins. Parietal bones large and in contact mesially ; 

 premaxilla forming margin of upper jaw. Vertebral centra as delicate cylinders, with 

 transverse processes bearing the ribs. No overlapping scales ; but paired longitudinal 

 series of bony scutes. Cretaceous. 



Dercetis, Agassiz. Snout elongated and pointed ; teeth minute and 

 clustered. Dorsal fin occupying greater part of back, and pelvic fins inserted 

 opposite to it ; anal fin short, opposite hinder end of dorsal ; caudal fin forked. 

 Dermal scutes more or less angulated and ornamented with tubercles or spines ; 



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