166 J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



another species according to the author's description in 1892, which later approved 

 is adopted by P. Geaebner in his revision of the genus in 1907. P. sulcaius, 

 therefore, has 30 — 36-nerved leaves, much larger fruits, longer spikes, and so on. 



P. muricatus is recognized by the broad-petioled ovate-lanceolate submersed 

 leaves, the broad short-petioled early appearing floating leaves, conspicuously elong- 

 ated styles and particular fruits (see the fig. I). The anatomic topography of the stem 

 has the following aspect: epidermis without a pseudo-hypoderma but with numerous 

 bast bundles, one circle of scattered interlacunar bast- and vascular bundles, 0-endo- 

 dermis and 8 free central bundles with strong bast-sheaths (in the fig. more strongly 

 hatched). In the trio the bundles are sometimes more fused, sometimes, again, more 

 free from each other, thus forming a transition to the foregoing group. Except those 

 bundle-sheaths there is no mechanic tissue in the pith. 



Distribution. Australia: »N. S. Wales, Major Vicary, 1836, 7» (lib. Stock- 

 holm.). Another station is: N. S. Wales, Tia River near Walcha, where it is gath- 

 ered by J. H. Maiden, 1897. 



P. sainai'iformis n. sp. 



Gaulis liumiHs teres simplex, ramo unico prolongatus. Folia submersa sessilia, 

 lanceolata, basi attenuata, apice obtusa, 7 — 9 cm longa, 7 — 10 mm lata, 7-nervia, 

 nervo medio non lacunosa, summa natantia ovalia obtusa obscure cuspidata, 

 basi ovata vel obscure cordata, 35 — 45 X 16 — 20 mm, 13-nervia petiolata petiolis 

 brevioribus (ca. 30 mm longis). Ligulm tenues badiae deciduse, ca. 20 mm longse. 

 Pedunculus teres, non incrassatus ca. 30 mm longus. Sjnca deflorata 23 — 25 mm 

 longa, 7 — 8- verticil] ata. Pistillum stylo subalato conspicuo, stigmate ovali parvo. 

 Fructus compressus, 3 X 2,5 mm, psene circularis, sinuose alato-carinatus, rostratus 

 rostro alato. 



The anatomical diagram of the stem is characterized bj' an epidermis without 

 pseudo-hypoderma, numerous subepidermal bast-bundles but no cortical strands, 

 0-endodermis and an eight-bundled central cylinder. 



The plants here concerned might be mistaken for P. similis A. Benn., but 

 differ by longer submersed leaves which are 7-nerved and obtuse, by the absence of 

 a lacunar areolation along the midvein, by the even peduncle, and by the fruit lacking 

 bosses at the base. 



I have seen specimens only from »Nov. Holland, austr., Dr Behr», coll. by 

 F. MtJLLER (hb. Kristiania), named P. nutans R. Br. 



P. tricarinatus F. Muller & Ar. Bennett. 



In the Journal of Botany, 1892, 229. 



The stigma of this species is oblong and as to about half its length free from the 

 style (see fig.!). The stem anatomy does not essentially differ from that of the 



