(7) A. BENNETT. POTÀMOGETONES OF THE HERBARIUM BOISSIER. 253 



a living spécimen. The oldest spécimen I can (ind in European herberia 

 is 1841-2 (Herb. Melvill) galhered near Philadelphia. 



25. P. densus L. Sp. pi. éd. 1, 183 (1753). 



The herberium contains good oriental spécimens which are very rare 

 in herberia. 



26. P. Hillii Morong Coult. Bol. Gaz, 6, 290 (1881). 



2 spécimens from the prov. of Hupah, China (D r Henry). Unfortunally 

 none of the spécimens I hâve seen from D 1 ' Henry hâve any fruit, hence 

 the identification is not quite certain. If correct it is interesting to find a 

 N. American plant reproduced in central China. Unforlunately at the place 

 given, I) 1- Morong's figure of the fruit of his plant wilh olhers of zoster- 

 folius, and acutifolius are not characleristic; of the last species, the only 

 good drawing. I hâve seen of the fruit is Reichenbachs in the Icônes, 

 Neither Chamissos, Fieber's or Eng. Botany are good. 



27. P. pauciflorus Pursh Fl. Am. Sept. 1, 121 (1814). 



D r Morong uses Rafinesque's name P. foliosus Rafn. Med. Rep. 2 d. 

 Hex. 354 (1808), « becaue Lamark used pauciflorus as a synonym of P. 

 densus L. » : I fail lo see the reason in this no one ever thinks of reviving 

 thèse names, and they are well understood. Spécimens of this from the 

 Sandwich Islands in the herberium are interesting, as the only others 

 I know of are in the Berlin herberium. 



28. P. Friesii Ruprecht Beitr. zur Pflan. Russ. Reichs 4, 43 (1845). 

 In herberium sub non « P. obtusifolius Met K.» Every herberium I hâve 



seen contains spécimens of this species (or. subsp.), but under the most 

 varions names; viz zosterifolius, acutifolius, obtusifolius, compressus, gra- 

 mineus, etc., etc. It certainly is the least understood of the graminifolius 

 section of the genus. Good spécimens are in the herb De Candolle gat- 

 hered by Reynier as early as 1821 in Switzerland. 



29. P. pusillus L. Sp. pi. éd. 1, 127 (1753). 



A species under which very unlike plants are associated,but so protean 

 are its forms fchat it seems impossible to limit them at présent in any 

 understandable way. 



34. P. gemmiparus (Robbins) Morong. Mon. N. Am. Naid., t. 54, 

 p. 47 (1893). 



This very curious plant requires carefull study in situ. D r Robbins 

 refered it to pusillus as a var. with a query. For some remarks on it see 

 Savageau « Journal de Botanique », 1894. 



35. P. Phialae Post in Bull. Herb. Boiss. I, p. 409 (1893). 



I cannot seperale this plant from P. trichoides Cham., exceptthat itis 



