30 ZYGNEMATACEAE 



spores formed in the conjugating tubes, compressed-globose, with the 

 longer diameter at right angles to the conjugating tubes; 25-27/^ x 

 30-33A1; median spore wall [?] brown, smooth. 

 Ireland. 



33. Zygnema circumcarinatum Czurda 1930. Beih. Bot. Zen- 



tralbl. 47, p. 53, Fig. 15. 



Vegetative cells 20-22/11 in diameter; conjugation scalariform; zygo- 

 spores formed in the conjugating tubes, globose or compressed-globose, 

 24M to 29A1 in diameter; median spore wall golden-brown, thick, scro- 

 biculate, with pits 2-2.5 m '" diameter and 1-2/^ apart; spore wall more 

 or less carinate. As the spores mature the tube walls change to pectic 

 compounds and form persistent colloidal walls as thick as the spores 

 themselves. This often results in separation of the spores from their 

 subtending gametangia. Aplanospores similar but smaller, often 

 maturing outside the sporogenous cell. (PI. IV, Figs. 8-9.) 



United States: Texas, Eden, April 13, 1938 (Taft Coll.). 



Bohemia. 



In Handbuch der Pflanzenanatomie (6, Conjugatae) Czurda discusses 

 and figures stages in conjugation, and germination of spores of this species, 

 which he had cultivated. 



Exactly similar stages in spore maturation occur in several species of 

 Mougeotia (PI. XVII). Note that the spores are also of the compressed type. 



34. Zygnema pawhuskae Taft 1934. Trans. Amer. Micros. Soc. 



53, p. 209, PI. 21, Fig. 61. 



Vegetative cells 21-24/'. ^ 40-60 /x; conjugation scalariform; zygo- 

 spores formed in the conjugating tubes, ovoid to compressed-globose, 

 extending into the gametangia, 34-48 /x x 46-65/1; median spore wall 

 seal-brown, of 2 layers, the outer smooth with a distinct equatorial 

 suture, the inner densely and minutely verrucose, sometimes reticulate- 

 verrucose. During the early stages of conjugation the outer sporangium 

 wall is a pectic layer 3-6 /i in thickness. (PI. IV, Fig. 10.) 



United States: Oklahoma. 



35. Zygnema carinatum Taft 1934. Trans. Amer. Micros. Soc. 



53, p. 210, PI. 17, Fig. 9. 



Vegetative cells 16-18/1 x 33-36 /<•; conjugation scalariform; zygo- 

 spores formed in the conjugating tubes, compressed-globose, with the 

 longer axis at right angles to the conjugating tube, 23-26/t x 29-33/i; 

 median spore wall blue, punctate, and encircled by a prominent suture. 

 During development the sporangium wall is encased in a pectic layer 

 3-6 /x in thickness. (PI. IV, Fig. 11.) 



United States: Oklahoma. 



