CHARACTERS OF TRIBES AND GENERA. 361 



marks it as a very distinct species. In the "United 

 States' Exploring- Expedition " it is spoken of as the " little 

 tree Fern." This presents a great contrast to Osmunda 

 regalis and Todea barbara ; these produce from their axis a 

 dense mass of aerial outgrowing mossy roots, which increase 

 in bulk with age, and in which the early axis of the verna- 

 tion becomes imbedded, its apex continuing to maintain its 

 position on the surface by the successive evolution of the 

 fronds, and often producing offsets (csespitose) ; numerous 

 crowns of fronds are thus formed, and which continue to 

 develope rootlets from their base, thus gradually increasing 

 the size of the spongy mass. By this mode of increase 

 specimens of 0. regalis attain the height of 2 or more feet, 

 with a diameter about the same, but this is exceeded in 

 size by Todea barbara, specimens of it having been received 

 in Europe from the Victorian Alps in Australia, one 

 measuring 5 feet 8 inches in height, its diameter being 7 

 feet 9 inches, its weight 1 ton 3 cwt. In 1869 a specimen 

 was received at Kew weighing 15 cwt., having 30 crowns, 

 producing 160 fronds, the weight of these great masses 

 being due to their being retentive of water like a sponge. 



DIVISION HI. SCAPHOBRYA. 



Fronds terminal, rising from between two stipuliform or 

 socket-like appendages, and articulate with the caudex. 

 Sporangia opaque, horny, destitute of a ring. 



Tribe 28. MARATTIE^ (Plate 28). 



MARATTIACE.E, Kaulf. 

 Vernation terminal, articulate. 



OBS. Although this tribe agrees with the whole of the 

 preceding in the fronds being spirally developed, it is 



