9(6) Sporangia often with pigmented walls, yellowish when young, finally grey or black, with well marked columella left after spore dispersal. Individual sporangiophores observable with unaided eye, up to 20mm long. _Mucor_ (fig. 68) e.g. spores smooth, 7-8 × 2.5-4.5µm - _M. hiemalis_ spores smooth, 6-12 x 3-6µm - _M. mucedo_ spores asperulate, 5-8.µm diam. - _M. plumbeus_ (N.B. _Zygorhynchus_ would key out with _Mucor_. It is more often isolated from soil, and is distinguished from _Mucor_ by the presence of zygospores with unequal suspensors) - Sporangia white, without a columella, readily becoming a spore droplet. Sporangiophores delicate, often only 200-400µm long. Fine, white, garlic-smelling mycelium often present. _Mortierella_ (fig. 72) e.g. spores 16-27µm diam, few in each sporangium; sporangiophores ca 150µm, with short lateral branches at right angles - _M. reticulata_ spores 6-10 x 4-6µm; sporangiophores 2-3mm high, with ascending branches - _M. bainieri_ spores 4-10µm; sporangiophores richly branched - _M. candelabrum_ 10(5) Sporangioles formed at the final tips of a densely dichotomous system of branchlets, originating some distance below a terminal sporangium (which may be absent in young specimens). Sporangioles up to 25µm diam., with up to 6 spores. Spores 8-12 × 6-8µm. _Thamnidium elegans_ (fig. 70) - Sporangioles either at the curved tips of slender branches, or clustered in groups about halfway along tapering branches which radiate from the sporangiophore below the sporangium; the branch tips of the latter give the fertile portion of the sporangiophore a bristly appearance. _Helicostylum_ (fig. 73) e.g. spores 8-17 × 3-7µm; sporangioles on short secondary or tertiary branches; fertile region bristly with sterile branches - _H. fresenii_ spores 6-8 × 4µm; sporangioles reflexed, on slender primary or secondary branches; fertile region without sterile branches - _H. pyriforme_ 11(1) Spores formed in chains. 12 - Spores formed singly. 14