326 TRANSACTIONS OF THE [Sess. lxxxiii 



United States, the Rev. E. J. Hill, in the Bot. Gazette, 260 

 (1881), may here be quoted under P. pert'olintiis: " Nearly 

 all the plants gathered in the West have the lanceolate 

 leaf, usually shorter than in the tj'pe specimen (var. 

 lanceolatux, Robbins). They gradually vary with all 

 degrees of difference between the variety and the typical 

 species, so that it is often hard to tell to which they should 

 be assigned." This is in the field, not herbarium study. 

 It was this great difference that made me hesitate to make 

 the variety mand'^Jiurieyisls, Ar. Benn., a species. Dr. 

 Hagstrom seems to think it may be so, and I believe the 

 winged fruit is not the result of drying ; hence it may be 

 considered a species. 



F. huplearoides, Fernald (United States). — This seems 

 very near perfoliatus according to Dr. Hagstrom, but I 

 have not seen specimens, and the only real difference seems 

 the smaller fruit. , 



I should here like to mention a note by an ornithologist, 

 Mr. C. B. Ticehurst, in Trans. Norf . and Nor. Nat. Soc, 1 95 

 (1918): "The affinities of most, if not all, animals are to 

 be sought in the earlier stages of development rather than 

 in the adult " ; and again at p. 200 : " The greatest advance- 

 ment in ornithology in modern times is, I consider, the 

 recognition of suh.s2')ecies, or racial forms." These two 

 remarks are exactly what my late friend Fryer always 

 pleaded for in Potamogetons. Lastly, how rich the 

 Scandinavian herbaria are in this genus, collectors' names, 

 etc., appearing that ours do not possess. Why ^ And 

 unqualiffed thanks must be given to Dr. Hagstrom for 

 the excellent use he has made of them, as a result of 

 twenty-five years'' study. 



We are not yet in a position to dogmatise on many 

 points of the genus. The naming of individual examples 

 from small areas, without collating with those already 

 named, is a mistake. They are valuable if accepted as 

 results of local conditions, environment, climate, etc., but 

 they are simply steps in evolution. 



