HISTORY.
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| Sub-classis III.—Ganoidei. | |||
| Ordo I.—Holostei. | |||
| Fam. 1. | Lepidosteini. | ||
| " 2. | Polypterini. | ||
| Ordo II.—Chondrostei. | |||
| Fam. 1. | Acipenserini. | ||
| " 2. | Spatulariæ. | ||
| Sub-classis IV.—Elasmobranchi s. Selachii. | |||
| Ordo I.—Plagiostomi. | |||
| Sub-ordo I.—Squalidæ. | |||
| Fam. 1. | Scyllia. | Fam. 6. | Rhinodontes. |
| " 2. | Nyctitantes. | " 7. | Notidani. |
| " 3. | Lamnoidei. | " 8. | Spinaces. |
| " 4. | Alopeciæ. | " 9. | Scymnoidei. |
| " 5. | Cestraciones. | " 10. | Squatinæ. |
| Sub-ordo II.—Rajidæ. | |||
| Fam. 11. | Squatinorajæ. | Fam. 14. | Trygones. |
| " 12. | Torpedines. | " 15. | Myliobatides. |
| " 13. | Rajæ. | " 16. | Cephalopteræ. |
| Ordo II.—Holocephali. | |||
| Fam. 1. | Chimaeræ. | ||
| Sub-classis V.—Marsipobranchii s. Cyclostomi. | |||
| Ordo I.—Hyperoartii. | |||
| Fam. 1. | Petromyzonini. | ||
| Ordo II.—Hyperotreti. | |||
| Fam. 1. | Myxinoidei. | ||
| Sub-classis VI.—Leptocardii. | |||
| Ordo I.—Amphioxini. | |||
| Fam. 1. | Amphioxini. | ||
Discovery of Ceratodus.
The discovery (in the year 1871) of a living representative of a genus hitherto believed to be long extinct, Ceratodus,
