Judging from my experience in Illinois it is highly probable that the list of North American forms will be considerably augmented, when intensive studies have been made at localities in the Southern United States. The most satisfactory method of collecting these forms is to take samples from the various ponds and streams at regular intervals of ten days, or two weeks, throughout the growing season. Many of the species show local variations and considerable experience is needed before many of the forms can be satisfactorily classified. The writer has in course of preparation an illustrated key to the group, in which figures for all of the species will be published. =DEBARYA= Wittrock. This genus is in many respects the most generalized of all the _Zygnemales_. It is distinguished by three important characteristics: (1) the entire contents of the gametangia enter into the making of the zygospore; (2) the zygospore is formed in the conjugating tube and is not cut off from the other parts of the gametangia by partition walls; (3) as the gametes move toward the tube during conjugation, their place is taken by a secretion of cellulose, which renders the gametangia solid and highly refractive. This secretion also occurs when a vegetative cell forms an aplanospore. =Debarya glyptosperma= Wittrock. This species has been recorded for America. It is not uncommon in Massachusetts and has also been found in Minnesota and Florida. In P. B.-A. No. 808 from Boswell, California is a somewhat smaller variety with blue spores associated with _Zygnema peliosporum_ Wittr. The spores are common in the material and the vegetative cells and filaments occasional. Following is a diagnosis for this variety: Var. =formosa= nov. var. Cellulis vegetativis 7.5-9µ latis; zygosporis 24-30µ × 30-42µ, caeruleis; ceterum ut in typo. Vegetative cells 7.5-9µ in diameter, zygospores 24-30µ × 30-42µ steel blue, otherwise like the type. =Debarya americana= nov. sp. Cellulis vegetativis 9-12µ × 27-120µ, ad dissepimenta constrictis; chromatophoris cum pyrenoidibus 2; cellulis fructiferis, 10-14µ × 75-180µ; zygosporis ovoideis vel quadrato-ovoideis, 20-40µ × 30-40µ, angulis rotundatis, productis, vel retusis; parthenosporis 15-20µ × 20-30µ, oblique ellipticis, cum polis retusis; mesosporio subtiliter et irregulariter verrucoso, maturitate luteo-brunneo. Vegetative cells 9-12µ × 27-120µ constricted at the end walls, chromatophore with two pyrenoids; fertile cells 10-14µ × 75-180µ; zygospores ovoid or quadrately ovoid, 20-40µ × 30-40µ, with angles rounded, produced, or retuse; parthenospores 15-20µ-× 20-30µ unilaterally ellipsoid with retuse ends; median spore wall minutely and irregularly verrucose, yellow-brown at maturity.