Nov., 1915] Notes on the Zygnemales 19 



X 20-30)U unilaterally ellipsoid with retuse ends; median spore 

 wall minutely and irregularly verrucose, yellow-brown at 

 maturity. 



This species was collected by Professor A. B. Klugh, Kings- 

 ton, Ontario. It is the material upon which the Ontario record 

 for Moiigeotia 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 16-20^ x 25-50^ cylindraceis ; chromato- 

 phoris asteroidiis duobus, singulis cum pyrenoidibus (ut in 

 Zygnemate) ; zygosporis vel ovoideis, vel irregularibus, 24-30/x 

 X 30-48^ cum angulis vel rotundatis, vel retusis, vel productis; 

 aplanosporis uno latere ovoideis, 17-25^ x 20-40^1; parthen- 

 osporis 15-20/>i x 20-30/x; membrana media sporarum scrobicu- 

 lata, luteo-brunnea ; akinetis ad dissepimenta constrictis, mem- 

 brana subcrassa et glabra, 18-20/^ x 20-36/x. 



Vegetative cells 16-20^ x 25-50/x cylindrical; chromatophores 

 two, stellate, each with a pyrenoid (as in Zygnema) ; zygospores 

 ovoid, quadrate-ovoid, or irregular, 24-30/i x 30-48/x, with 

 rounded, retuse, or produced angles; aplanospores unilaterally 

 ovoid, 17-25At x 20-40iu; parthenospores 15-20/^ x 20-30yu; median 

 spore walls scrobiculate, yellow-brown; akinetes with smooth 

 heavy walls, 18-20^ x 20-30)U. 



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 



