EEVISION OF THE GENUS XAJAS. 415 



squamulis intra vaginali bus anguste lineari-subulatis ; florihus in ramulis brcvibus 



diclinis ; spatha niascula oblonga, superne in collum breve, ore longe spiniferum, 



attenuata; ovario nudo suboblongo, stylo cylindrico, in stigmata duo diviso; fructu 



lineari-oblongo ; semine ruguloso cum areolis quadrilatcralibus clongatis in sericbus 



numerosis lineato, raphe valde distiiicta. 



Plants slender and delicate, 10 to 10 cm. high according to Mouong ; stems almost 



filiform, branching from the base, rooting at the nodes ; branches spreading. Lower 



internodes 1-5 to 4 cm. long, diminishing to about 1 cm. a few centimetres below the 



apex. Leaf-blade often at an angle with the well-developed sheath, generally 2 to 



2'5 cm. long, but reaching 3 cm., and scarcely '25 mm. or less in width. Apex ending 



in one or two sharj) spines; margin with about 7 or 8 distant teeth, absentfrom the lower 



part ; teeth small, projecting slightly, consisting of sharp ascending spine-cells raised 



above the margin on two cells or on a shallowly triangular few-celled process. Sheaths 



1'5 to 2*5 mm. long, auricles bearing 4 to 6 large, irregular, brown-spine-bearing teeth. 



Intravaginal scales about '75 mm. long. 



Flowers borne on short axillary shoots, male and female occurring on the same shoot. 

 Male 1'5 mm. long ; spathe oblong, narrowing below and passing above into a narrowly 

 obconical neck, the mouth of which bears several (4) long, sharp, brown spines ; perianth 

 as usual, as also dehiscence of anther on elongation of the pedicel. Ovary about 2 mm. 

 long ; one of the two stigmas was on one occasion seen to end in a brown spine. Fruit 

 subsessile, 2'6 to 33 mm. long, narrowing at the a2)cx and slightly falcate, crowned by 

 the withered style ; pericarp when dry thin and membranous, conforming closely to the 

 seed. Testa bearing numerous longitudinal rows of four-sided areolae, about twice as 

 long as broad, becoming fewer and irregular at the ends. 



Eastern United States — Rhode Island [Lenormand) ; Albany (Engelmami) ; 

 Missouri {Engelmami) ; Bristol, Pennsylvania ; Boston (Booth). 



19. Najas Kingii, sp. nov. (PL XLI. figs. 126-131.) 



Monoica, ramis longis effusis apice dense ramulosis ; follis longis lineari-angustatis, 



margine cum dentibus ascendentibus pluribus obtuse triangulis aculeiferis, laminae 



latitudinis dimidium aequantibus vel brevioribus, instructa, nervo mediano et lineis 



brevibus horizontalibus conspicuis ; vagmis magnis, marginibus late imbricatis, basi 



attenuatis, superne truncate rotundatis et dense dentatis ; squamulis intravagin- 



alibus minutis, e basi latiore filiformibus ; Jloribus illis N. foceolatce similibus ; 



fructu parvo ellipsoideo, jicricarpio tenui ad semen flavum conformante, testa cum 



areolis parvis subsexangulis manifeste notata. 



A unique specimen. Shoots long, straggling, ending in a dense bushy growth ; lower 



internodes 3 to 4 cm. or more long, generally about 7 mm., sometimes nearly 1 mm., in 



breadth. Leaves reaching, without the sheath, 3*5 cm. in length, with a width of '75 



mm. in the lower part ; apex uni- or bidentate ; each margin with 16 to 19 teeth, 



consisting of a small obtusely triangular outgrowth ending in a dark brown sharp spine. 



Sheath large and broad, with overl apping edges broadening upward from the base ; upper 



margin truncate, with broadly rounded shoulders bearing generally 10 teeth, which 



