36 INTRODUCTION 



ter of an inch, is reported by one author to be seven hundred feet 

 in length, by another fifteen hundre feet. It is terminated by 

 a lamina fifty feet long, resembling a pinnatifid leaf, each leaflet 

 of which, at its point of division on the stem, expands into an 

 air-vessel as large as an egg. These air-vessels sustain the 

 immense frond which floats on the surface of the water, its leaf- 

 lets depending in a vertical position from the stem. M. pyrifera, 

 the only species, is found in the Southern oceans and on the 

 Pacific coast of North America. 



Lessonia, another genus, resembles a palm-tree. It grows 

 erect to a great height and has a stem like the bole of a tree. 

 It branches in a forking manner and has depending from its 

 branches laminae two or three feet long. The large stems from 

 which the laminae have been torn by the storms, and which have 

 been cast ashore on the Falkland Islands, as described by Sir 

 Joseph Hooker, resemble driftwood, as they lie in piles three or 

 four feet high and extending for many miles. 



Agarum and Thalassiopliyllum are arctic genera, but they are 

 found within our limits, the former in the North Atlantic. It 

 has a simple but enormous leaf-like frond. The latter, which is 

 found on the North Pacific coast, has a compound frond. Both 

 are characterized by their fronds being perforated throughout 

 with holes, giving them the name of sea-colander. 



