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plant in Berlin museum has a serrulated leaf-margin and 
for the rest has nothing of P. prælongus, and the Swedish 
P. upsaliensis Tis., which absolutely has nothing to do with 
P. prælongus, and the english P. Babingtonii, that is mere 
P. prælongus and nothing else. (By the way may be pointed 
out that we have but one P. decipiens Nolte, viz. lucens -f- 
perfoliatus). Likewise with P. capensis Scheele, etc. 
As to P. ziziiformis, its natural place is close to P. 
lucens and allied, what group properly could be named 
»dentati». 
It belongs to the flora of Brazil, where it is collected 
1892 by C. Lindman. 
Potamogeton dentatus n. sp. 
Caulis ca. 50 cm altus teres ramosus internodiis ca. 
4 — 5 cm longis; folia omnia uniformia submersa membrana- 
cea lanceolata petiolata longe mucronata acute et minu- 
tissime dentata, quoad nervaturam P. lucenti simillima; 
folia caulina 7-nervia (nervis tenuissimis marginalibus ex- 
ceptis) nervis longitudinalibus omnibus ad basin mucronis 
confluentibus, ca. 80 mm longa et 20 mm lata, petiolo 5—15 
mm longo, mucrone plus minus 10 mm, ramea minora, 
° ~1 5^ ~' mm ’ mucrone petioloque brevioribus sed inter se 
eadem longitudine; stipulas intraf oliaceæ 20—40 mm longæ 
amplæ membranaceæ persistentes subfuscæ obtusæ bico- 
statæ costis ad basin stipulæ crassitudinem ejusdem 6-plo 
superantibus; pedunculus inconspicue incrassatus 50—100 
mm longus; spica deflorata 50—60 mm longa; fructus par- 
vus, 2 mm longus, 1,75 mm latus complanatus suborbiculatus 
vel oblique obovatus, rostro brevi subapicali, dorso siccus 
subcarinato. 
The anatomy of the stem is almost congruent to that 
of P. gramineus L. -{- lucens L. (P. Zizii M. & K.). Along 
the epidermis is an often interrupted single layer of paren- 
chyma. Interlacunar vascular and bast-bundles occur in 
the cortex in two circles, the innermost of them with few 
