On American Species of the Genus Potamogeton. 347 



It appears that the eyes of an individual are not a pair in the 

 sense of the word as applied to gloves — the one designed for the 

 right and the other for the left hand, but two alike, performing 

 the office of vision just as well if their places should be changed! 

 This offers a perfectly satisfactory answer to the question — why 

 we do not see objects double with two eyes. 



Art. XXX. 



Potam 



>/ 



(Continued from vol. vi, p. 224.) 



The following notes, as well as those already printed in this 

 Journal, have been in every instance derived from examinations 

 of living plants, enlarged by subsequent comparison of dried 

 specimens. The terminology is that of Chamisso's Monography ; 

 and beside this, reference has been made constantly to the revision 



etons by Fries, in his Novitice, and to 

 jvucii s synopsis 01 me German Flora. I may be permitted to 

 add that I owe to Professor Nolte, of the University of Kiel, who 

 has pursued for many years the study of these plants, which he 

 has illustrated in his Novitia?, and elsewhere, — and who first di- 

 rected my attention to them, a large and invaluable set of the 

 species of Schleswig and Holstein. 



Potamogeton nat ans 7 (L.): caule simplici tereti ; foliis omni- 

 bus ionge petiolatis, natantibus coriaceis subcoriaceisve ovato- 

 ellipticis basi ssepius cordatis apice obtusiusculis submucronatis ob- 

 longis ellipticisve multinervibus, petiolis concaviusculo-eonvexis ; 

 petiolis submersis inferioribus aphyllis acuminatis; stipulis elon- 

 gatis lineari-linguiformibus acutis; pedunculis crassis subasquali- 

 bus foliis brevioribus; spicis cylindricis densifloris; fructibus re- 

 centibus oblique obovatiusculis, stylo brevi facialiapiculatis, dorso 

 arcuato obtusiuscule carinalis, lateribus convexis in faciem acutiu- 



sculam declivibus. 



Fr. Chamiss. 



in Linnma, 2, 217, t vi, f. 20. Fr. Novit. PL Suec., p. 28. 

 Koch. Syn., p. 672, A. Gray! Man. Bot., p. 455, a. Wood 

 BoL, p. 524, e descr. 



Hab. In stagnant and in flowing water; common in New 



England. The description was taken from specimens growing 

 in stagnant pools near Lake Champlain, at Burlington, Vt., which 

 agree generally with specimens from other parts of New Eng- 

 land, and from Western New York, [Dr. Sartwell!) Fl. June and 

 July. Fr. August and September. Stems simple, terete, many 

 arising from the creeping root. Leaves all on long footstalks; 

 the lowest bladeless and acuminate ; the others ascending toward 



