540 HISTORY OF THE HUMAN BODY 



Division II. Gnathostomata. 

 Super-Class I. Ichthyoidea. 

 Class I. Pisces. 



Sub-Class I. Elasmobranchii. 



Order I. Pleuropterygii (Cladoselache). 

 Order 2. Ichthyotomi (P I eur acanthus}. 

 Order 3. Acanthodii (Acanthodes, Di pi acanthus). 

 Order 4. Selachii. 



Sub-Order i. Squali (sharks, dog-fish). 

 Sub-Order 2. Raiae (skates). 

 Sub-Class II. Holocephali.* 



Order i. Chimaeroidei * (Chimera). 

 Sub-Class III. Dipnoi.* 



Order i. Sirenoidei * (Protopterus, Ceratodus). 

 Order 2. Arthrodira (Coccosteus, Dinichthys). 

 Sub-Class IV. Teleostomi. 

 Order i. Crossopterygii.* 



Sub-Order i. Haplistia (Tarrasius). 



Sub-Order 2. Rhipidistia (Holoptychius; Oste- 



olepis). 



Sub-Order 3. Actinistia (Ccelacanthus ; Undina). 

 Sub-Order 4. Polypteroidei * (Polypterus; Cala- 



moichthys). 

 Order 2. Actinopterygii. 



Sub-Order i. Chondrostei * (Palcconiscus; Aci- 



penser, sturgeon). 

 Sub-Order 2. Protospondyli * (Lepidotus; Eu- 



gnathus; Amia, bow-fin). 

 Sub-Order 3. -ZEtheospondyli * (Aspidorhynchus; 



Lcpisostcus, gar-pike). 

 Sub-Order 4. Isospondyli (Lcptolepis; herring; 



salmon; trout). 

 Sub-Order 5. Eventognathi (carp; minnow; 



sucker). 



Sub-Order 6. Nematognathi (siluroids, e.g. bull- 

 heads, cat-fish, etc.). 

 Sub-Order 7. Haplomi (pike; killifish). 

 Sub-Order 8. Apodes (eels). 

 Sub-Order 9. Synentognathi (flying-fish). 



