The vegetative cells are usually shorter than in _S. nitida_, the spores are ovoid, not ellipsoid, and the spore wall is verrucose, or reticulate-verrucose, chestnut brown in color. In herb. E. N. T. Coll. No. 2900.
Var. =formosa= nov. var. Varietas gracilis, cellulis vegetativis 80-95µ × 80-270µ; zygosporis 88-100µ × 120-150µ × 70-90µ; ceterum ut in typo.
A small variety, vegetative cells 80-95µ × 80-270µ: zygospores 88-100µ × 120-150µ × 70-90µ; otherwise similar to the type. Type in herb. E. N. T. Coll. No. 1939. This variety occurs in a pond east of Ashmore, Ill.
This species which was described from Illinois has been found with nearly the same dimensions in the collections from Middlesex Fells, and South Peabody Station, Mass., sent me by Mr. Chas. Bullard.
Cellulis vegetativis 30-36µ × 120-300µ, dissepimentis planis, chromatophoris singulis anfractibus arctis 3-7; cellulis fructiferis modo binis vel quaternis inter cellulas vegetativas distributis, modo continuis, altero latere (in quo conjugatio sequitur) inflatis, altero rectis; tubo conjugationis plerumque ex cellula mascula emisso; zygosporis ellipticis 37-42µ × 57-100µ membrana media micropunctata et lutea.
Vegetative cells 30-36µ × 120-300µ, end walls plane; 1 chromatophore making 3-7 turns; fertile cells scattered in twos or fours among vegetative cells, or continuous, inflated on the conjugating side, outer side straight; conjugating tubes formed almost wholly by the male cell, zygospores ellipsoid 37-42µ × 57-70µ, median wall minutely punctate, yellow. Type in herb. E. N. T. Coll. No. 2470, 2953.
This species was first found in the West Big Four Pond, east of Charleston, Illinois. It has since been found in a collection from Chocorua, N. H., sent me by Mr. Chas. Bullard. It evidently belongs in the _punctata_ group of the Spirogyras, but in form and markings of the spore, and the shape of the fertile cells it is amply distinct from its nearest allies; _S. punctiformis_ Transeau and the next species to be described.
Cellulis vegetativis 30-40µ × 120-300µ, dissepimentis planis; chromatophoris singulis anfractibus arctis 3-8 cellulis fructiferis binis vel quaternis inter cellulas vegetativas distributis, inflatis et valde reflexis; tubo conjugationis ex cellula mascula emisso; zygosporis ellipticis, 44-54µ × 90-150µ, membrana media glabra et luteo-brunnea.