58 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



writer has already expressed his behef that these two great 

 divisions of the Spermaphytes are of entirely distinct origin. 

 If we accept the view that there is a probable direct connec- 

 tion of the Monocotyledons with the Pteridophytes, it is 

 among just such simply organized aquatics as Naias or Zan- 

 nichellia that we should naturally look for the point of con- 

 tact. It is true that these are generally looked upon as 

 degenerate types derived from apocarpous forms, like 

 Alisma or Butomus (Delpino, 1896; Bessey, 1893); but 

 there seems no good reason for such an assumption. 

 Inasmuch as nearly all the heterosporous Filicinese, includ- 

 ing Isoetes, are either aquatic or at least amphibious, it 

 would naturally be expected that forms derived from them 

 would inherit their aquatic habits, and the simple tissues 

 which accompany such a habit. We should also expect 

 in such forms an extremely simple type of flower, such as 

 really exists in JVaias. Taking into account, then, all of 

 the similarities of the tissues of the mature plants, as well as 

 the similarities in the embryo and sporangia, it may safely 

 be said that at any rate the theory of a direct derivation of 

 the Monocotyledons from forms related to the heterosporous 

 Filicinese, and especially the Isoetaceas, is not weakened by 

 what has been brought out in the course of these investi- 

 gations. 



As to the relationship of Naias and Zannichellia to each 

 other, it does not seem sufficient to warrant uniting them in 

 the same family, although they are with little question not 

 very distantly related. For a clear understanding of their 

 relationship to the other apocarpous Monocotyledons, further 

 investigations of these forms will be necessary before we 

 are in a position to decide with any degree of certainty. 



LELAND STANFORD JUNIOR UNIVERSITY, 

 CALIFORNIA, 



January, 1897. 



