D 
1 
The front view resembles that of Arthrodesimis convergens, Ralfs, 
but the triangular end view proves it to be quite distinct. 
St. Anthony Park and other localities, Minn. 
St. VESICULATUM, ;/. ^/.— Small, smooth, about one-half longer 
than wide; constriction deep, sinuses acute angled, much ampliated; 
semi-cell short, ovate or sub-pyramidal, not so long as broad; base 
wide, lower angles rounded, sides convex and inclining to the rounded 
apex; end view triangular, angles rather broadly rounded, sides 
slightly convex or straight. Diameter 31/^; length 4,5//. 
Differs from St, cordatum^ F. Gay, in front view; sinuses are not 
narrow linear, but much ampliated, thereby giving the cell a more 
elevated appearance. 
Green's Lake, New Jersey. 
Si. bacillare^ Breb. (Figs. 5 and 6).— Near Minneapolis, Minn. 
Brebisson describes a form of a French species as Si. globosiim which 
s somewhat stouter and partially granular, but nearly similar in form; 
the two have therefore been very properly considered as one by 
recent botanists. 
Si. Maamcnse^ Archer i^St. pseudocrenatiim, Lund.) (Figs 9 and 
10).— St. Anthony's Park, near Minneapolis, Minn. 
As Archer's name antedates Lundell's, it is entitled to stand. 
Si. erasum^ Breb., forma espiiinlosa^ Lund. (Figs, 16 and 17). 
Green's Lake, New Jersey. 
St. xiPHiDioPHORUM, 11. sp. (Figs. 2 1 and 21). — Small, one-half 
longer than broad; deeply constricted, sinus narrow, rounded at base 
and widened irregularly; semi-cell transversely oblong, with lateral 
margins notched; the end margin drawn out into a sort of one- 
sided, hastate, poignard-like spines, or slender points, about nine in 
number; membrane smooth, with several scrobiculae; end view trian- 
gular, angles broadly truncate and usually three-lobed, each lobe 
with a vertical spine; sides concave. Diameter 25-30/^; length 40/^. 
Near Stillwater and Minneapolis, Minn. 
When sending me this beautiful and remarkable little Siatirastrum, 
Miss Butler called my attention to *' i/ie little gothic structure,'' a very 
appropriate comparison. 
St. MiNNEAPOUENSE, 11. Sp. (Figs. 11-13).— Small, verrucose; 
semi-cells in front view subcuneate, with each of the two opposite 
superior angles drawn out into a short arm, with sides serrate and 
'^pex finely toothed, diverging from the arm of the connected semi- 
cell; end view, arms straight,^ body much elevated on each side; side- 
view, arms straight, body much raised in the centre and crenate on 
the apex. Diameter, f. v., 50-58/^; thickness of body 20-25 //. 
The front view not unlike other species, but the side and end 
views quite distinct in the unusual inflation of the body. 
St. calyxoides, tu sp. (Figs. 14 and 15).— Nearly equal ui length 
and breadth; smooth or finely punctate; deeply constricted; semi- 
cells saucer- or calyx-shaped, bearing on the undulate margin five 
equally distant divergent spines; end view pentagonal, each angle 
produced and bearing a strong aculeus. Diameter about 33/^, with- 
out, and 75/i with, the aculei. 
Near Manchester, Ocean Co., and Green's Lake, Warren Co., New 
Jersey. 
