544 TELEOSTEI CHAP. 



I. Fins fringed with fulcra, or scales coated with ganoin ; notochord 

 usually continuous through the vertebrae. 



Vertebral centra not more than rings ; fins with fulcra ; scales rhombic, 

 united by peg-and-socket joints ... 1. Pholidophoridae. f 



Vertebral centra not more than rings ; fins with fulcra ; scales cycloid 



2. Archaeomaenidae. f 



Vertebral centra complete or with minute perforation ; fins with fulcra ; 

 scales cycloid ....... 3. Oligopleuridae. f 



Vertebral centra nearly complete, but with perforation ; no fulcra ; scales 

 cycloid ....... 4. Leptolepididae. f 



II. Fins without fulcra ; scales without ganoin ; vertebral centra com- 

 plete. 



A. Supraoccipital separated from the froiitals by the parietals or upper 

 surface of skull ; no adipose fin. 



1. Ventral fins with 10 to 16 rays. 



An intergular bone ; parasphenoid narrow . . 5. Elopidae. 

 No intergular bone ; parasphenoid very broad . 6. Albulidae. 



2. Ventrals with not more than 7 rays. 



a. Supratemporal very large, plate-like. 



Praemaxillary single, its posterior extremity free from the maxillary ; sym- 

 plectic absent ; basis cranii simple ... 7. Mormyridae. 



Praemaxillary paired, its posterior extremity firmly attached to the maxil- 

 lary ; symplectic present ; basis cranii double . 8. Hyodontidae. 



b. Supratemporal small ; maxillary firmly attached to posterior 



extremity of praemaxillary. 

 Praemaxillary paired ; a large hole on each side of the skull, between the 



post-frontal and the squamosal ; basis cranii double ; suboperculum absent ; 



ribs sessile ....... 9. Notopteridae. 



Praemaxillary paired ; basis cranii simple ; suboperculum reduced ; ribs 



inserted on parapophyses . . . .10. Osteoglossidae. 

 Praemaxillary single ; basis cranii simple ; suboperculum and interoperculum 



absent ; ribs inserted on parapophyses . . 11. Pantodontidae. 



c. Supratemporal small ; maxillary movable ; ribs sessile ; 



ventral fins below the pectorals 12. Ctenothrissidae. f 



B. Supraoccipital separating parietals, or adipose fin present. 



1. Interoperculum enormous ; symplectic absent ; basis cranii simple 



13. Phractolaemidae. 



2. luteroperculum normal ; symplectic present ; basis cranii double. 



a. Teeth in sockets ; maxillary firmly attached to praemaxillary. 

 Symplectic exposed . . . . . .14. Saurodontidae. f 



b. Teeth not in sockets. 



Symplectic concealed between the quadrate and the hvomandibular 



1 5 . Chirocen tridae. 

 Postclavicle on outer side of clavicle ; no adipose fin 



16. Clupeidae. 

 Postclavicle on inner side of clavicle ; an adipose dorsal fin 



17. Salmonidae. 

 Postclavicle absent ; no adipose fin . . .18. Alepocephalidae. 



t This sign indicates that the group is represented by fossil forms only. 



