164 Prof. E. D. Cope on the Systematic Relations of Fishes, 



I. A precoracoicl arch. 

 A. A coronoid bone. 



Maxillary in many pieces ; vertebra? opistliocoelian. 3. Gin- 

 (jlymodi (the Bony Gar). 



Maxillary not transversely divided ; vertebras ampliicoelian. 

 4. lialecomorphi (the Dogfish). 

 AA. No coronoid bone. 



* No symplectic bone. 



Pterotic simple ; anterior vertebras with ossicula auditiis ; 

 supraoccipital and parietals coossified. 5. Nematoijnatld (the 

 Catfishes). 



Pterotic annular, including a cavity closed by a special 

 bone ; parietals distinct ; vertebrse simple. 6. Scyphoiyhori 

 (the Mormyri). 



** Symplectic present. 



Anterior vertebras coossified, and with ossicula auditus. 



7. Plectospondyli (the Suckers &c.). 



Anterior vertebras similar, distinct, without ossicula auditus. 



8. Isospondyli (Herring &c.). 



II. No precoracoid arch. 



A. Scapular arch suspended to cranium. 



* A symplectic. 



Pterotic and anterior vertebras simple ; parietal separated 

 by supraoccipital. 9. Haplomi (Pike &c.). 



Anterior vertebras modified ; parietals united ; ])ectoral fins. 

 10. Glanencheli (Electric Eel). 



** No symplectic. 



Anterior vertebrte simple ; a prceoperculum and maxillary ; 

 no pectoral fins. 11. Ichthyoceiihali (Java Eels). 

 AA. Scapular arch free behind the cranium. 



* A prteoperculum. 



A symplectic ; maxillary well developed ; no pectoral fins. 



12. Ilolostomi (Symbranchi). 



No symplectic ; maxillary lost or connate ; pectoral fins. 



13. Enchelycephali (Eels proper). 



** Prgeoperculum wanting or rudimental. 



No symplectic, maxillary, or pectoral fins, no pterygoid. 



14. Colocephali (Murasnas). 



Of the above orders the Haplomi (Pike &c.) approach 

 nearest the Physoclysti of the families Ophiocephalidas and 

 Atherinidas, and the Holostomi of the family Symbranchidas 

 to the Physoclyst family of Mastacembelida. The affinities 

 between these families are in both cases so close as to render 

 the distinction of the primary divisions in question hardly 

 worth preserving. 



The complete development of the support of the caudal fin 



