GROUP III. PTER1DOPHVTA. 379 



Section Eusporangiatse. Each sporangium is developed from 

 a group of superficial cells. 



Order 1. Ophioglossacece. Order 2. Marattiacece. 



Section Leptosporangiatae. Each sporangium is developed 

 from a single superficial cell. (Filices in limited sense). 



Order 1. Osmundaceoe. Order 4. Poly pod iacece. 



,, 2. Schizceacece. 5. Cyatheacece. 



3. Gleicheniaceoe. ,, 6. Hymenophyllacece. 



Sub-Class HETEROSPOREJS. The sporophyte produces micro- 

 spores and macrospores ; the former give rise to male, the latter 

 to female, prothallia ; the prothallia do not become free from the 

 spore. 



Section Eusporang'iatae. Each sporangium is developed from 

 a group of superficial cells. 



Order 1. Isoetacece. 



Section Leptosporangiatae. Each sporangium is developed 

 from a single superficial cell, (Khizocarpge or Hydropterideee). 



Order 1. Salviniacece. Or.der 2. Marsileacece. 



Class VI. EQUISETIN^E. The sporophyte is characterised by 

 the well-developed branched stem, with small whorled leaves 

 forming a sheath at each node ; the small peltate sporophylls are 

 aggregated into a cone-like flower at the apex of each fertile shoot, 

 and bear a few sporangia on the inner (inferior) surface ; the 

 archesporium is a single cell ; the embryo has a primary root 

 and no suspensor. All the existing forms are homosporous and 

 eusporangiate. 



The gametophyte is a free, green, membranous prothallium, 

 generally dioecious ; the spermatozoids are multiciliate. 



Order 1. E quisetacece. 



Class VI T. LYCOPODIISLE. The sporophyte is characterised 

 by the well-developed branched stem with numerous small scattered 

 leaves ; the sporangia are borne singly either on the upper surface 

 of a sporophyll, or on the stem ; the sporophylls resemble the 

 foliage-leaves, but are sometimes aggregated into cone-like flowers ; 



