ZYGOGONIUM 65 



3. Zygospores 15-26/U, x 20-36 ju,, sporan- 

 gium suture indistinct i. Z. ericetorum 



3. Zygospores 13-17 m x 19-32 /x, sporan- 

 gium suture prominent 2. Z. mirabile 



3. Zygospores 20-25 ju, x 18-25 /"-, sporan- 

 gium with pectic wall 3- 2^- pectosum 



4. Zygospore median wall scrobiculate or punctate 5 



4. Zygospore median wall with pits, or marginal arched ridges 6 

 5. Zygospores without distinct suture, me- 

 dian wall punctate 8. Z. punctatiim 



5. Zygospores without distinct suture. ... 9. Z.heydrichii 

 5. Zygospores in sporangia having collars 



at both ends 14. Z. stephensiae 



5. Zygospores with distinct suture 10. Z.sinense 



6. Zygospores with scattered pits on 



median wall 1 1. Z. exuvidlijorme 



6. Zygospores with arching ribs on 



one side of suture 12. Z. plal^ountiosporum 



7. Spore walls probably smooth at maturity 8 



7. Spore walls not smooth when mature 9 



8. Diameter vegetative cells 10-14 /n, 



spores usually terminal 7. Z. kumaoense 



8. Diameter vegetative cells 12-20^, 



spores usually lateral 5. Z. talguppense 



9. Diameter vegetative cells 8-12/1, spore 



wall verrucose 4. Z. hansgirgii 



9. Diameter vegetative cells 16-20 ij^, spore 



wall scrobiculate 6. Z. capense 



Descriptions of Species 



I. Zygogonium ericetorum Kiitzing 1843. Phycologia Generalis, 

 p. 446. 



Vegetative cells 12-33 m x io-ioom; chromatophores 2, stellate, pil- 

 low-form or indefinite, each with a central pyrenoid; filaments branched 

 or unbranched; conjugation scalariform. Zygospores develop within 

 definite sporangia formed by the conjugating tubes and cut oflf by a 

 wall from the adjoining gametangia. Zygospores ovoid or ellipsoid, 

 1 5-26 /J. X 20-36 /i, thick-walled, smooth; aplanospores globose or ovoid, 

 occupying only a part of the original cell, 15-20 /x x 15-40 /x; wall 

 smooth. (PL X, Figs. 10-16.) 



United States: Known to occur on acid soils, in ponds and peat bogs 

 throughout the coastal plain from Maine to Mississippi, and in Ohio, Mich- 



