GENEKA OF EEKNS AND THEIR CLASSIFICATION. 71 



Division I. — Eremolrya. 

 Fronds articulated with the rhizome. 

 Tribe I. Oleandrea?. — Sori round, medial, intra -marginal. 



sium lateral, interiorly attached, or sometimes central 

 plane. 



II. Davallese. — Sori round, terminal, marginal. Indusium 

 lateral, interiorly attached, vertically urceolate. 



III. Polypodese. — Sori round or linear, naked. 



Division II. — Desmobrya. 



Fronds adherent to the stem. 



Tribe IV. Acrosticheoe. — Sori amorphous, naked. 



V. Grammiteoe. — Sori oblong or linear, simple, forked, or 

 reticulated, naked. 



VI. Phegopteridese. — Sori round, rarely linear, naked or 

 indusiate. Indusium lateral, ulteriorly attached or 

 central, or rarely calyciform. 



VII. Pteridese. — Sori marginal, round, or linear and trans- 

 verse. Indusium lateral, exteriorly attached on the 

 margin. 



VIII. Blechnea?. — Sori intra-marginal, linear, transverse. 

 Indusium lateral, exteriorly attached. 

 IX. Asplenea?. — Sori linear, oblique. Indusium lateral. 

 X. Dicksonea?.— Sori marginal, round, or linear and 

 transverse. Indusmm lateral, interiorly attached, 

 conniving with the changed margin, forming a groove 

 or urceolate sub-bivalved cyst. 



XI. Cyatheoe. — Sori round, intra-marginal. Receptacles 

 elevated. — Indusium calyciform, or lateral and inte- 

 ' riorly attached or absent. 



Sub-Order II.— Glcicheniaccce. 

 Ring horizontal {Sori intra-marginal.) 



Sub-Order III. — Hymenophyllacece. 

 Ring horizontal or oblique. {Sori marginal.) 



