Sumstine: North American Mucorales 127 



Sporangiophores arising from the mycelium, spo- 

 rangial membrane not cuticularized. 



Sporangiophores long, with metallic luster. 



Sporangiophores variable in length, white, 

 gray, brown. 



Sporangiophores brown or brownish with 

 spiny aerial filaments. 

 Sporangiophores arising from the mycelium or 

 from mycelial swelling, sporangial mem- 

 brane cuticularized. 



Sporangiophores arising from mycelial swell- 

 ings. 



Sporangiophores not as above. 



3. Phycomyces. 



Hydrophora. 



5. Spinellus, 



Hydrogera. 



PiLAIRA. 



2. Ramosi 

 Sporangiophores variously branched. 



Sporangiophores dichotomously branched. 

 Sporangiophores without terminal sporangia, 



branches circinate. 

 Sporangiophores with terminal sporangia, branches 

 with sporangioles. 

 Sporangioles on dichotomous branches. 

 Sporangioles on circinate branches. 

 Sporangioles on straight branches, arising 

 from bulbs. 

 Sporangiophores with sporangia only. 



Branches long or short, zygospores with nearly 



equal suspensors. 

 Branches as above, zygospores on dichotomous 

 branches, suspensors unequal. 



Syzygites. 



9. CiRCINELLA. 



10. Thamnidium. 

 12. Helicostylum. 



11. bulbothamnidium. 



13. Calyptromyces. 



14. 



Zygorhynchus. 



I. Mucor (Mich.) L., Sp. PI. 1185. 1753 

 Ascophora Tode, Fung. Meckl. i : 13. 1790. 



Type species, Ascophora Mitccdo Tocle. 

 Rhizopiis Ehrenb. Nov. Acta Acad. Leopold 10^: 198. 1820. 



Type species, Rhizopus ■nigricans Ehrenb. 



Original description : Fungus vesicula subrotunda, in qua 

 semina numerosa affixa, receptacuHs criniformibus constans. 

 Type species, Mucor Mucedo L. 



Sporangiophores simple, usually growing in clusters of two, 

 three, or five from the nodes of the stolons, enlarged below the 

 sporangia forming an apophysis ; mycelium white at first, then 

 brown, growing by stolons attached at different places to the 

 substratum by rhizoids; zygospores borne on the mycelium, 

 naked. 



