2 6 PHYCOMYCE TES 



The families and genera of the Mucorales can be distinguished 

 by the following table, adapted and abridged from Schroeter : 



1. Asexually-formed spores exclusively or predominately developed in 



sporangia which sometimes resemble conidia 2. 



Asexually-formed spores produced as conidia ; sporangia only excep- 

 tionally developed. ( Species parasitic on other moulds. ) II. 



2. Sporangia (at least the principal ones) with columella ; conidia forma- 



tion wanting or shghtly developed ; zygospore naked or. covered 

 with a loose growth from the suspensors.Fam. i. Mucoraceae. 3. 

 Sporangia without columella ; conidia present ; zygospores encased in 

 a thick covering. (Species parasitic on other moulds). 



Fam. 3. Mortierellaceae. 10. 



Family I. Mucoraceae. 



3. Sporangium membrane uniformly developed, not cuticularized, break- 



ing or melting away. 4. 



Sporangium membrane cuticuliarized in the upper half and persistent, 



thin and melting away in the lower half. 9. 



4. Sporangia all similar furnished with columella (only exceptionally in 



small lateral sporangia). 5. 



Sporangia of two kinds, principal and secondaiy ; principal at the end 



of hyphae always with a columella. 8. 



5. Sporangiophores simple or branched but not repeatedly dichotomous ; 



zygospores formed on the horizontal mycellium. 6. 



Sporangiophores repeatedly dichotomous ; zygospores on aerial 



hyphae. Sporodinia. 



6. Suspensors with no outgrowth at maturity. MUCOR. 

 Suspensors with a thorny outgrowth at matui-ity.- 7. 



7. Thorns of suspensor projecting ; zygospore naked. Phycomyces. 

 Thorns closed over the zygospore forming a loose covering. Absidia. 



8. Principal sporangia with columella, secondary without ; spores uniform 



in both. Thamxidium. 



Principal sporangia with columella, those of the secondary tongue- 

 shaped ; spores different in two kinds of sporangia. Dicranophora. 



9. Sporangiophores uniformly cylindric under the sporangium ; sporangia 



not discharged. PiLAIRA. 



Sporangiophores swollen under the sporangium ; sporangia forcibly 



discharged at maturity. PiLOBOLUS. 



