THE AMPHIBIOUS QUILLWORTS. 243 



necticut. When first discovered they were referred to 



Isoctcs Eatoni, but a later opinion is that the plants are 



specifically distinct. In the shape and 



size of the spore they resemble that 



species, but the markings are more 



like those of Isoctes riparia. As in Iso- 



etes Eatoni the microspores are seldom Me<?asporeof 



Isottes Gravesii. 



round. 



The plants have from fifty to seventy-five leaves, 

 which are erect and sharp-pointed, and possess four bast 

 bundles. The indusium is narrow, and the sporangium 

 light cinnamon colour. The megaspores are from 35O/" 

 to 400^ in diameter, greatly flattened in the upper hemi- 

 sphere, and densely covered with stout truncate, mostly 

 single columns. The shape of the spores is very charac- 

 teristic. It is difficult to believe that a species of this 

 genus should be restricted to so small a region, and the 

 idea suggests itself that this is still another form of the 

 species which goes under the name of Isoctcs Engelmanni 

 valida or Isoctes Eatoni. The author would be inclined 

 to call it Isoctcs valida Gravesii. The presence of the 

 bast bundles in the leaves, the small size of the mega- 

 spores, and the marked flattening they display, the lack 

 of microspores, and the dioecious nature of the plant, all 

 point to a close relationship to the form described as 

 Isoetes Eatoni, and Mr. Eaton writes that if this plant is 

 ever reduced to a variety it must be made a variety 

 of this form. 



Isoetes Melanospora. 



This peculiar species was discovered in 1869 by 

 Canby, who found it growing in shallow excavations in 

 granite rock on Stone Mountain, Georgia. It is remark- 



