GENERA OP FERNS AND THEIR CLASSIFICATION. 71 



Division I. Eremolrya. 

 Fronds articulated with the rhizome. 

 Tribe I. Oleandrese. Sori round, medial, intra -marginal. 



sium lateral, interiorly attached, or sometimes central 



plane. 



II. Davalleoe. Sori round, terminal, marginal. Indusium 

 lateral, interiorly attached, vertically urceolate. 



III. Polypodese. Sori round or linear, naked. 



Division II. Desmolrya. 

 Fronds adherent to the stem. 

 Tribe IV. Acrostichese. Sori amorphous, naked. 



V. Grammitese. Sori oblong or linear, simple, forked, or 

 reticulated, naked. 



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

 indusiate. Indusium lateral, interiorly attached or 

 central, or rarely calyciform. 



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

 verse. Indusium lateral, exteriorly attached on the 

 margin. 



VIII. Blechnese. Sori intra-marginal, linear, transverse. 



Indusium lateral, exteriorly attached. 

 IX. Aspleneae. Sori linear, oblique. Indusium lateral. 

 X. Dicksonese. Sori marginal, round, or linear and 

 transverse. Indusium lateral, interiorly attached, 

 conniving with the changed margin, forming a groove 

 or urceolate sub-bivalved cyst. 



XI. Cyathese. Sori round, intra-marginal. Eeceptacles 

 elevated. Indusium calyciform, or lateral and inte- 

 riorly attached or absent. 



Sub-Order II. Gleicheniacece. 

 Eing horizontal. (Sori intra-marginal.) 



Sub-Order III. Hymenophyllacece. 

 Ring horizontal or oblique. (Sori marginal.) 



