THE AQUATIC QUILLWORTS. 229 



named Isoctis lucroglypliua. It is described as having 



ten to twenty leaves two or three inches long, which 



are recurved and somewhat blunt at the tip. The 



sporangium is unspotted and about one third indusiate. 



The megaspores are very characteristic, 



being- from 485/* to 590 ^^ in diameter, 



and marked, except near the equator, 



with rather large wormlike ridges. The 



body of the spore is quite smooth and 



greyish in colour. The microspores 



are from ^i /* to 44^ loncf and are warty. 



^ ^^ "^ -' Megaspore of 



In outward appearance the plant has fortes hierogiyphu.i. 

 great resemblance to Isoetcs Tuckermaiii, to which it is 

 no doubt closely related, though the spore characters are 

 distinctive. 



Isoetes Ma count. 



Isoetes Macouni is known to grow only on Atka Island, 

 off tlie coast of Alaska, from whence it was brought by 

 J. M. Macoun in 1891. The plants were found in a 

 pool on the side of an extinct volcano, and apparently 

 in such a position as to be always submerged. The 

 leaves are from five to twelve in number, 

 about two inches long, and quite stout. 

 The megaspores average about 450^ in 

 diameter and are set with stout blunt 

 spinules usually about twice as long as 

 broad. The microspores are finely and 



Megaspore of ^ ^ •' 



isottcs Macouni. dcuscly papiUose and about 40/' long. It 

 is possible that this is still another form of Isoetes ecliino- 

 spora. It has considerable resemblance to the variety 

 Flettii, and the differences it presents may be due to its 

 habitat. 



