Potamogeton. | CLIII. NAIADACEZ (BENNETT), 223 
Schweinfurth refers his 896 to P. pusillum, and also 769 (collected at Acrur in 
Eritrea), which I have not seen. This plant has been named P. javanicus, Hassk., 
but its affinities are with P. Hillii, Morong, and P. acutifolius, Link, on the one 
side, and P. foliosus, var. californicus, Morong, on the other; more remotely (in 
foliage only) with P. javanicus, Hassk. A specimen in herb. Boissier, (Yemen, 
Arabia, Deflers) may be referred here, but the material is poor. 
10. P. pectinatum, Linn. Sp. Pl. ed. i. 127. Stem cylindrical or 
Subcompressed, repeatedly branched. Leaves all similar, or the upper 
sometimes setaceous and l-nerved, the lower linear and 1-3-nerved ; 
stipules long, adnate to the sheathing petiole, free at the apex. 
Peduncles short or long, equal in diameter throughout; spike often 
interrupted ; upper flowers generally approximate. Fruit large, olive 
or green, obliquely obovate, slightly compressed, slightly convex on the 
ventral margin, 3-keeled on the dorsal.—Peters, Reise Mossamb. Bot. 
511; Durand & Schinz, Conspect. Fl. Afr. v. 495. P. marinum, 
Linn. ? ex Krauss in Flora, 1845, 344. 
Upper Guinea. Gold Coast : Cape Coast Castle, Don! 
Mile Land. Abyssinia: Tigre; Mai Gouagoua, Quartin-Dillon ! 
Lower Guinea. Angola: Mossamedes; in deep ponds near Aguadas, Welwttsch, 
250! German South-west Africa, ex Durand & Schinz. 
_ Mozamb. Dist. Portuguese East Africa : Lower Zambesi, in the large lake 
of Shupanga, Peters ! 
Also in North and South Africa, Socotra and the Mascarene Islands. 
11. P. filiforme, Pers. Syn. i. 152. Stem filiform, branched, 
Leaves all similar, setaceous (or linear-setaceous), 1-nerved, usually 
much stouter than the peduncles; stipules slender, adnate to the 
Sheathing petiole, free at the apex. Peduncles slender, long, equal in 
diameter throughout; spike much interrupted, but in a much more 
regular manner than in P. pectinatum, as the fruits are usually in whorls. 
Fruit much smaller than in P. pectinatum, with the beak central and the 
margins rounded. ; 
East Tropical Africa. Ruwenzori Expedition: without precise locality, 
Scott-Elliot ! . 
Widely distributed in all warm and temperate regions. 
_ 12. P. Livingstonei, Arth. Bennett. Stem from a slightly creep- 
Ing rhizome, thick at the base, with a strong annulus at the base of 
the leaves. Leaves densely packed at the base of the stem; lower 
leaves resembling those of a Cymodocea in texture, 2}-3 in. long, 
3-5; in. broad, thick, half-folded at the base, flat towards the apex, 
d-nerved, with numerous waved cross veins, rigid, spreading-erect, and 
deeply striated ; middle leaves less rigid, 1-3-nerved, with the adnate 
stipules large and entire at the apex; upper leaves linear-filiform, 
1-3-nerved. Peduncles short; spikes short. No fruit seen. 
Mozamb. Dist. British Central Africa: Lake Nyasa ; in the south-western 
