THE TERRESTRIAL QUILLWORTS. 



253 



small — fj-om 250," to 500^ in diameter. The megaspores 

 ai'e very characteristic, being white or light grey in 

 colour, with a peculiar glassy lustre, as 

 though made of porcelain. They are 

 marked by small, regular warts, •v;hich are 

 sometimes so minute as to be barely 

 distinguishable. They have the greatest 

 resemblance to the spores of Isoctcs Bo- 

 landcri, and the two might be regarded isoS^f^Nuluua. 

 as forms of a single species, one growing beneath the 

 water and the other modified for an aerial existence. 

 The two are found in the same general region, Isoctcs 

 Nuttallii being reported from California to British Co- 

 lumbia and Idaho. 



Isoetes Orcutti. 



The plants referred to Isoctcs Orcutti belong to the 

 same general group of which Isoctcs Nuttallii may be 

 taken as the type. The megaspores, howe\er, are \'er)' 

 smooth, at best having onlv a faint granular appearance. 

 They have the same glassy lustre as those of Isoctcs 

 Nuttallii and are dark blue-grey in colour. The indu- 

 sium is entire. From resemblances of the spores, 

 indusium, and habitat, the author has no doubt that this 

 is a southern form of Isoctcs A^uttallii, and 

 believes it would be better characterised 

 by calling it Isoctcs Nuttallii Orcutti. 



The leaves of tliis form are few, from 

 two to four inches long, and contain 

 from two to four bast bundles. The 

 megaspores are from 240." to 300.'' in di- 

 ameter, and the microspores are dark 



Megaspore of 

 Isoetes Orcutti, 



