This species was collected by Professor A. B. Klugh, Kingston, Ontario. It is the material upon which the Ontario record for _Mougeotia calcarea_ (Cleve) Wittr. is based. Of special interest is the chromatophore with two pyrenoids, which although an axile plate is distinctly two-lobed and forms an easy transition to the next species, in which the chromatophore resembles _Zygnema_. Type in herb. E. N. T. Collection No. 2950. =Debarya decussata= nov. sp. Cellulis vegetativis 16-20µ × 25-50µ cylindraceis; chromatophoris asteroidiis duobus, singulis cum pyrenoidibus (ut in Zygnemate); zygosporis vel ovoideis, vel irregularibus, 24-30µ × 30-48µ cum angulis vel rotundatis, vel retusis, vel productis; aplanosporis uno latere ovoideis, 17-25µ × 20-40µ; parthenosporis 15-20µ × 20-30µ; membrana media sporarum scrobiculata, luteo-brunnea; akinetis ad dissepimenta constrictis, membrana subcrassa et glabra, 18-20µ × 20-36µ. Vegetative cells 16-20µ × 25-50µ cylindrical; chromatophores two, stellate, each with a pyrenoid (as in Zygnema); zygospores ovoid, quadrate-ovoid, or irregular, 24-30µ × 30-48µ, with rounded, retuse, or produced angles; aplanospores unilaterally ovoid, 17-25µ × 20-40µ; parthenospores 15-20µ × 20-30µ; median spore walls scrobiculate, yellow-brown; akinetes with smooth heavy walls, 18-20µ × 20-30µ. Type in herb, E. N. T. Collections No. 1177, 1939, 1949, 2686 and 2918. I have specimens from several localities in central Illinois; Williamsport, Pa.; Minnesota; Mackinaw, Mich. and Kingston, Ontario. This form is of great interest because of its resemblance, in the vegetative condition, to _Zygnema decussatum_ (Vauch.) Transeau. Also because it shows not only the zygospores, but aplanospores and parthenospores. In all cases the secretion of cellulose accompanies the process of spore formation. The unilaterally placed aplanospores are strikingly different from those formed by the Zygnemas. In some of the Illinois ponds it regularly produces only zygospores, in other ponds from which I have collections covering a period of several years it fruited only asexually, producing aplanospores and akinetes. But several of the collections show all the forms of reproduction in different cells of the same filament. The characteristics of this species suggest that the peculiar _Zygnema reticulatum_, which was described by Hallas in 1895[B], is in reality a _Debarya_. The fact that the reproductive cells become filled with cellulose, that the aplanospores are very irregular in form and that the vegetative cells contain as high as seven chromatophores, are all in harmony with this idea. On this basis it is also easy to understand the most notable peculiarity of the species—that spores derived from cells with several chromatophores produce two or three sporelings. With the addition of the two new American species and this Danish species =Debarya reticulata= (Hallas) nov. comb. the description of the genus needs to be modified as follows: