CHARACTERS or TRIBES AND GENERA. 361 



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

 States' Exploring Expedition " it is spoken of as tlie " little 

 tree Fern." This presents a great contrast to Osmunda 

 regalis and Todea harhara ; these produce from their axis a 

 dense mass of aerial outgrowing- mossy roots, -which increase 

 m bulk -5vith 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 (ctespitose) ; numerous 

 crowns of fronds are thus formed, and which continue to 

 develope rootlets fi-om 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 harhara, 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 18G9 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 III.— SCAPHOBRTA. 



Fronds terminal, rising from between two stipuliform or 

 socket-like appendages, and articulate with the caudex. 

 Sporangia opaque, horny, destitute of a ring-. 



Trihe 28.— MAEATTIE^ (Plate 28). 

 Maeattiaceje, Kaulf. 

 Vernation terminal, articulate. 



Obs. — Although this tribe agrees with the whole of the 

 preceding in the fronds being spirally developed, it is 



