498 FISHES CHAP. 
bodied Holosteans with rhombic scales, rarely, as in Aetheolepis, 
cycloid in the caudal region. All the fins possess fulera. Teeth 
more or less conical, with a tendency to become tritoral in certain 
genera. Jugular plate present or absent. Acentrophorus (Upper 
Permian); Semionotus (Trias of England, Germany, 8. Africa, 
and N. America); Lepidotus (Fig. 292) (Trias of Germany, 
Jurassic of Europe and India, Cretaceous of Brazil); the deep- 
bodied Dapedius (Lias of Dorset, Fig. 293), and Aetheolepis 
(Jurassic of New South Wales) are characteristic genera. 
Fic. 293.—Restoration of Dapedius politus. Lower Jurassic, Dorset. x 4. 
(After Smith Woodward.) 
Fam. 2. Macrosemiidae.—Closely related to the Semionotidae, 
but with a more extended dorsal fin. Macrosemius (Upper 
- Jurassic of England, Germany, France); Notagogus (Upper Jurassic 
of Naples, Bavaria, France); Petalopteryx (Upper Cretaceous of 
Syria). 
Fam. 3. Pycnodontidae.—Highly specialised deep - bodied 
Fishes, with a small mouth and characteristic yrinding or 
tritoral teeth. Scales rhombic. Fulcra absent. Dorsal and 
anal fins long. There is no jugular plate. The family ranges 
from the Lower Lias to the Lower Eocene, inclusive. J/esodon, 
Mesturus, Gyrodus, and Microdon are Jurassic genera. Coccodus 
and Xenopholis occur in the Upper Cretaceous of Syria (Mount 
Lebanon), and Pyenodus in various, European Eocene formations. 
Fam, 4. Eugnathidae.—Large - mouthed, elongate fusiform 
