154 THE AMERICAN MONTHLY [July, 



prominent near the base of the semicell, its outline fading into 

 that of the semicell one-third the distance toward the apex. In 

 front view it has nearly the outline of E. crassum. Cytioderm 

 granulate. Diameter about 80-85 m. Length nearly 2^ times as 

 much. Published October 27, '88. 



Xanthidium truncatum, spec. nov.. Hastings. (A', ajiti- 

 l()pceu7)i, var. truncatuvi^ Hast. Oct. 20, ^Z^. X. Tayloriamim, 

 West, Jour. Roy. Mic. Soc. Jan. '89.) Plate i, fig 2a, 2b, 2c, 

 X 500.) Cells longer than wide ; cytioderm finely granulate ; semi- 

 cells truncate-pyramidal in front view ; four pairs geminate re- 

 curved spines to each semicell, those at the superior angles de- 

 flexed horizontally and continuous with the truncate or slightly 

 convex ends of cell ; short conical central protuberance beaded 

 with about 20 granules in outer circle : side view of semicell nearly 

 circular ; end view oval, ends of oval emarginate between the pro- 

 jecting spines. Diameter 55-60 m. without spines, with spines 

 75-80 m. Ponds and streams, Rochester, N. H. Oct. 20, '88. 



Staurastrum megalonotum (Xord.), var. obtusum, var. 

 nov. Hast. (Plate i, fig. 35X500.) Cells small, about one- 

 fourth longer than broad ; cytioderm granulate ; isthmus about 

 one-half width of cell ; sinus acute angled, ampliated outwardlv ; 

 semicells truncately pyramidal, base convex ; sides concave, the 

 truncate ends with six conical processes, only four of which are 

 usually visible in front view, basal angles obtuse (differing in this 

 respect from Arctic varieties) ; transverse view triangular, the 

 angles rounded, the sides slightly concave. Diameter 45 m. Ponds 

 and streams Rochester, N. H. Sept. 8, '%'Z. 



Closterium robustum, spec. nov. Hast. (Plate i, fig. 4, 

 x 250.) Cells large, semi-lunar, a little more than four times as 

 long as wide ; cytioderm smooth ; dorsum high convex ; ventrum 

 somewhat concave, ventricose ; chloropliyl globules large, nu- 

 mei-ous, scattered ; vacuoles large, terminal, distinct, with many 

 moving granules. Empty cells colorless. Diameter 100-120 m. 

 Page Brook, Rochester, N. H. Dec. 26, '90. 



Closterium maculatum, spec. nov. Hast. Plate i, fig. 5. 

 x 500.) Cells very slightlv curved, tapering but slightly until near 

 the ends, which are attenuated at the expense of the ventral side, 

 giving them a turned appearance, but without depression on upper 

 side as in C. turgidum 16-32 times as long as wide; cytioderm 

 finely areolate and with about six interrupted stride, to which the 

 areolations give the appearance of dots, three or four together, 

 then a blank space followed by a collection of dots, and so alter- 

 nately. Diameter 25-30 ra. Ponds and brooks, Rochester, N. 

 H. Nov. 3, '88. 



Closterium lineatum, var. costatum, var. nov. Wolle. 

 (Plate I, fig. 6, X250.) Differs from usual form in having the 

 striae very thick and few in number (only six). Wolle has a 

 figure of a fruiting specimen in P. LXL f. 3, F. W. Alga;. Nov. 



