1863.] PONDWEEDS. 463 



to Eng. Bot. t. 2253, ought to settle the nomenclature of this 

 plant, at least in this country. P. pectinatus of Smith includes 

 P. marimis, and probably P. setaceus and P. flabellatus. 



In epitomizing the preceding history of the Pondweeds, the 

 following results have been elicited : — First, that these plants 

 were not separated from the marine Algse by Theophrastus, the 

 first genuine botanical author extant; second, that they were 

 observed and distinguished both by Dioscorides and Pliny, who 

 lived nearly four centuries after the age of Theophrastus ; and it 

 has also been remarked that both these ancient authors describe 

 under the name of Potamogeton, Polygonum amphihium, and this 

 has been the cause of much learned conjecture among their com- 

 mentators, editors, and translators. Sprengel indeed quotes Po- 

 tamogeton serratus as a synonym of Tribulus aquaticus, Theoph. 

 iv. 11, but the description is far from being that of any Potamo- 

 geton whatever. 



All British authors prior to Kay that have been consulted for 

 this monograph, viz. Lobel, Gerard, Parkinson, etc., retain 

 Polygonum amphibium among the Potamogetons, a sure proof 

 that their knowledge of these plants was not very profound. 

 Ray also, in the earlier editions of his works on botany, retained 

 the ancient arrangement, but he is the first British author who 

 put the plant in its right place, viz. among the Persicarias, and 

 asserted that it was not a Potamogeton. 



The modern history of these plants may be further studied in 

 the current works on the subject; it is only their ancient and 

 mediaeval condition that is embraced in this memoir. Something 

 about their topography or distribution in the fresh or brackish 

 waters of our Continent will be found in the sequel. 



All the species that grow in Great Britain are more or less 

 distributed in the inland waters of the Continent of Europe, and 

 probably some of them are not uncommon in other parts of the 

 world ; and as the number of the species which grow in the 

 British Isles has been doubled during the last twenty years, 

 great accessions to this Order may be expected when the botany 

 of other and remoter territories has been as successfully inves- 

 tigated as that of our native country. 



As before said, they grow generally in deep waters, or in 

 shallow waters where there is a considerable depth of mud. The 

 only one not strictly confined to such localities is Potamogeton 



