128 J. O. HAG5TP.ÖM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



apice rotundata?, in spatio intercarinali 7—8 nervige, ca. 12 mm longa?, biglandulosa?. 

 Spiea ignota. 



Anatomy eoincides nearlv with that of P. pusiUus except that the leaves, in 

 their upper half and sometimes also farther clown, are lacking the lacunar rowa along 

 the midrib, and on either side of it ahvays are furnished with verv thin, mechanical 

 strands scarcely perceivable to the naked eye. The topography of the central axi- 

 oi the stem i- of the circular type, and for the rest of pusilhis-stTuctuTe. 



This specir- oonatitutea an interesting combining link between the Oxyphylli 

 <['. and PusiUi (P. pusiUus) and would be ranked together with the 



former almost with the same right as with the latter. Ligules and leaf-apexes, how- 

 • r, unite it with the Pusitti. 



Distribution: ^reenland, probably endemie. It is gathered at Ivigtut (83, 

 Beslut), Christianshåb (90, Habtz), Jakobshavn (02, Söbensen), Kingua Orpiksnit, 

 30 X. L. (90, Habtz), Ritf-nbenk, 69° 44" (88, Hahseh) and at Sarkak, 70' X. L. 

 . Habtz). The materials are preserved in Hb. Univ. Copenhagen. 



Subeectio 14. Javanici Gbaebneb, in A. Kngf.kr, Das Pflanzenreich IV, 11, 



Potamog. 1907, 45. 



Gavlié fceree \<-\ rarius subcompressus, ramosus. Fclia semper biformia: vere 



oatantia brevipetiolata, paucinervia; submersa anguste linearia paucinervia in apicem 



acntom lenaim attennata, secundum röstarn mediam asepe valde laounosa. Ligula 



typice fissa-, in spatio medio paucinervia?. Stylus conspicuus vel subelongatus. Fruc- 



carinatua B&pe rugoeoe vel muricatus. 



Morpliologifully as well as anatomically and biologieally (the turios!) this group 

 niost cloaely asaociatea to the apeciefl of the puailloida which have Bubcoriaeeous in- 

 rolncral leaves, bnt exhibita alao affinity with the natans-group, to which P. Vaseyi 

 can be Baid to form the tranaition by its characteristic Bubmersed Leaves. 



The coriaceoua leavee exhibit the aimpleel atructure with small air-oella in the 

 appet Burface, a little larger in the lower Burface and, typieally, between those a 

 one-eelled layer, Beparating the apper and t hr- lower lacunas from each otber. öppet 

 Burfaee endowed with st omata. 



\ fai aa known to the writer the ligulea are open and convolute excepl in 

 the new ipeciea P. subjavanicué ra. in which they are connate at the ba 



to the fruit the group presents resemblance to the Compressi, Monogyni and 



M ni x ni, . 



The iteni anatomy of the Javanici differa (rom thal of the PusiUi by being typie- 

 ally endowed with b p eudo-hypoderma and by the croaa-oot form <>l' their central axis 

 being moatly rounded. In other arorda the anatomical oonditiona are tnore uniform 

 than in the group n<-\t before. But exoeptione oeeur alao here. 



