THE AMPHIBIOUS QUILLWORTS. 241 



reticulata and Palincri, respectively, have been found. 

 It is a remarkable fact that Isoetes riparia forms should 

 be found only at the head of Delaware Ba)-, and Isoctcs 

 saccharata forms only in similar situations in a neighbour- 

 ing bay, especially since the two are so closely related. 

 It would seem as if the progeny of a single species 

 settling in tlie region have been modified by the sur- 

 roundings until they have assumed their present forms. 

 Mr. Eaton apparently considers that Isoetes saccharata is 

 represented in New England, since he has recently 

 described the variety Amesii from Massaciiusetts. It 

 appears, however, better referred to Isoctcs Canadensis 

 Robbinsii. 



Isoetes Foveolata. 



W'hatever may be the status accorded this form, at 

 present, it is certainly closely related to Isoctcs Engel- 

 inanni. The patterns of the markings on the mega- 

 spores are almost identical, but there is so much differ- 

 ence in the thickness of tlie reticulations that the spores 

 present a very different appearance. 



Isoetes foveolata is a stouter, shorter plant than Isoctcs 

 . Engcbnannt, with from fifteen to sixty pinkish leaves two 

 to six inches long, bearing stomata 

 mostly near the tips. The peripheral /^'^^§^ 

 bast bundles are absent, and the spo- 

 rangia are thickly spotted with dark 

 cells whicli are often assembled into 

 groups. Some plants appear to bear 

 only megaspores. These are from 

 SSo/' to 560 M in diameter, flattened on /"S?>°"/°L 

 the hemisphere bearing the commis- 

 sures, and covered with reticulations so wide and so 



