PHANEROGAMS— PROFESSOR BAYLEY BALFOUR. 290 



B. flabelliformis, Linn. ; Mart. Hist. Palm. iii. 218, tt. 108, 121, 162. 

 B. ccthiopum, Mart. Hist. Palm. iii. 220, 318 ; Kuath Euum. iii. 223. 



Socotra. Occasional. B.C.S. n. 523. 



Distrib. Of the genus. 



A few individuals of this palm were seen here and there upon the island 



Order LXXX. NAIADACE^E. 



A not very extensive order of fresh and salt waters all over the world. 

 The three Socotran genera have a world-wide distribution. 



L POTAMOGETOK* 



Potamogeton, Linn. Gen. n. 174; Benth. et Hook. Gen. PI. iii. 1014 



A genus including many very variable species, the number of which has, 

 however, been inordinately multiplied. There are three species in Socotra all 

 cosmopolitan, but the Socotran form of one has a limited distribution, being 

 confined to Europe, though reported from Jamaica and Australia. 



1. P. natans, Linn. Sp. 182; Kunth Enum. iii. 127; Ach. Rich. Tent. 

 Flor. Abyss, ii. 354; Boiss. Flor. Orient, v. 15, 



Sub-sp. plantagineus, Du Croz in Rcem. et Schult. Syst. iii. 504 ; 

 Gaud. Flor. Helv. i. 471, t. 3; Eng.Bot. t. 1401. 



Socotra. B.C.S. n. 152. 



Distrib. Of the species — cosmopolitan. Of the sub-species — Europe, 

 Jamaica, Australia % 



This seems quite the plant of Du Croz ! with the exception of the upper 

 leaves, which are subcoriaceous, these are probably unknown (or extremely rare), 

 the nearest approach to these Socotran specimens are Hungarian from Dr 

 Kovdts, but the structure of the leaves leave little doubt (in the absence of 

 fruit). The general habit and leaf areolation comes about half-way between 

 typical P. plantagineus and Sicilian specimens doubtfully referred to P. siculus, 

 Birmi. 



The distribution of P. plantagineus seems to be bounded in the east by 

 Arabia. A similar instance occurs in P. densus, L., which . occurs in Greece 

 and then in Armenia, but also extends to north India. P. plantagineus is 

 usually supposed to be confined to Europe, but Grisebach has a variety of it 

 from Jamaica, which, in the absence of fruit, I have no reason to doubt. And 



* To Mr A. Bennett I am indebted for the determination of, and the subjoined notes to the species 

 of this genus. 



