206 EXERCISES. 



9. Describe the nature of the flora of the ancient earth, 

 and the peculiar climate indicated by such a character of 

 vegetation. 



10. State the period when this flora gradually assumed its 

 present European character. 



11. Commit to writing a list of the genera of fossil plants, 

 with the derivation of their respective names. 



12. Copy, on tracing paper, a typical specimen of each 

 genus. 



13. Seek to combine practice with theory, and identify 

 specimens of each genus with their description in books. 



14. Name the genera which most closely resemble each 

 other, and state the characters which distinguish odonto- 

 pteris from pecopteris, and the latter from neuropteris and 

 sphenopteris. 



15. Trace the leaves (with their venations) figured in 

 page 197. 



16. Trace in like manner a pinnate, bipinnate, and 

 tripinnate, and a ternate, biternate, and triternate leaf. 



17. Trace from the work of Brongniart the leaves (with 

 their venation) of recent ferns resembling the fossil species. 



18. State the distinction between caulopteris and sigil- 

 laria, and the reasons for establishing the former as a 

 separate genus. 



