172 MACOUN AND BUEGESS ON 



nia. The sporangia are usually collected in little masses called sori, which are oftenest found on the veins 

 or at the tips of the veins, and are often covered either by a little scale [mdummi) produced from the epider- 

 mal cells, or by a general involucre formed from the recurved margin of the frond or its divisions. 



Suborder 1. PoLYPODiACEiE. Sporangia globular, or slightly flattened laterally, collected in patches, lines or dots 

 of various shapes, stalked, and provided with a vertical incomplete many-jointed ring which straightens at 

 maturity and discharges the very minute spores, the sporangium opening by a transverse split across the 

 side not occupied by the ring. Terrestial ferns. 



Tribe I. Polypodise. Sori round or oblong, placed on the veins or at the ends of the veins ; indusiuni none. 

 Stalk articulated to a slightly prominent knob of the usually elongated creeping rootstock. Veins free or 

 variously reticulated. 



1. POLYPODIUM. The only genus of the (ril.o. 



Tribe IL Gramniitidea?. Sori more or less elongated, without indusiuni, superficial, placed on the back of 

 the frond or its divisions, and usually following the veins, or onl}' near the tips of tlie latter and near the 

 margin. Fronds sometimes scaly or tomentose, or covered beneath with coloured powder. 



2. GYIMNOGPiAJIlME. Sori much elongated, following the veins, and like them often branched or reticulated. 



Tribe III. Pterirtese. Sori close to the margin, sometimes extending partly down the veins, covered, at 

 least when young, by an involucre opening inwards and either consisting of the margin or produced from it. 



3. CHEILANTHES. Sori minute, at the ends of the unconnected veins, covered by a usually interrupted 

 involucre. Small ferns, often woolly, chaflfy or pulverulent. 



4. PELLyEA. Sori near the ends of the veins, often confluent. Involucre membranaceous, continuous round 

 the pinnules. Sterile and fertile fronds much alike and smooth ; the stalk dark-coloured. 



5. CRYPTOGRAMME. Sori extending down the free veins. Involucre very broad, at length flattened out and 

 exposing the now confluent .sori. Sterile and fertile fronds unlike, smooth ; the stalk light-coloured. 



6. PTERIS. Sporongia borne on a continuous vein-like marginal receptacle, which connects the ends of the 



veins. Involucre contiinious round tlie pinnules. Stalk light-coloured. 



7. ADIANTUM. Sporangia borne at the ends of the veins, on the under side of the reflexed margin of the 

 frond. Midvein of the pinnules mostly eccentric or dissipated into forking veinlets. Stalk dark-coloured. 



Tribe IV. Bleclliieœ. Sori more or less elongated, borne on a fruiting veinlet or on a special receptacle 

 parallel to the midrib, either near it or remote from it, and provided with a special usually concave or arched 

 indusium attached to the recejitacle outside the sorus and opening along the inner edge. 



8. LOMARIA. Sori continuous from the base of the pinna to its apex, the receptacle nearer the margin than 

 the midvein. Fronds in our species once pinnate, the fertile ones with contracted pinnse. 



9. WOODWARDIA. Sori interrupted, forming a chain-like row each side of the midvein. Fronds in our species 

 ample, compound ; the veins reticulated. 



Tribe V. AspIeniCie. Sori more or Icbs elongated, borne on veins oblique to the midvein, covered by a 

 special usually flattened indusium attached to the fertile veinlet by one edge and free on the other. 



10. ASPLENIUM. Sori on the upper side of the fertile veinlets, less commonly on both sides of them. Veins 

 free in our sjjecies. 



11. SCOLOPENDRIUM. Sori linear, straight, confluent in jiairs, borne facing each other on contiguous veins, 

 the two indusia meeting by their free edges over the sporangia, and at lengtli disclosing the latter between 

 them. Fronds simple and veins free in our species. 



12. CAMPTOSORUS. A^eins reticulated, manj- of the sori continuous along t«o or three sides of the aréoles, 

 and therefore bent or angled ; other sori opposite and facing each other in pairs, and some single on either 

 the upper or lower sides of the veins. Fronds simple, the apex slender and elongated. 



Tribe VI. Aspldife. Sori round or roundish, on the back, or sometimes at the tip, of the fertile veinlets, 

 naked or provided with a special indusium. Stalk not articulated to the rootstock, the tropical genus 

 Olcandra excepted. 



* Fertile and sterile fronds nearly alih'; receptacle not elevated. 

 t Indusium none. 



13. PI-IEGOPTERIS. Sori dot-like, minute. 



t + Indusium, orbicuJar or reniform. 



14. ASPIDIUM. Sori round, borne on the back or at the apex of the veinlets ; indusium attached at the centre 



