MUCO RALES 245 



neither incrusted nor thickened, thin, soon disintegrating; 

 columella conical to hemispherical, with a papillate apical 

 prolongation which is sometimes drawn out into a rather long 

 spine; sporangiospores small; zygospores borne on the stolons; 

 one or both suspensors provided with prominent circinate out- 

 growths which tend to envelope the zygospore (Fig. 81). 



The genus contains about twenty species. In its sporangial 

 characters it corresponds with Mycocladus, and in its possession 

 of stolons recalls Rhizopus. The genera Tieghemella Berlese 

 & de Toni (Saccardo Syll. Fung., 7: 215, 1888), Proabsidia 

 Vuillemin (1903 h: 119), Pseudoabsidia Bainier (1903: 153), 

 and Lichtheimia Vuillemin (1903 6: 119) are here, as in Lendner 

 (1908 b: 129), merged with Absidia. 



4. Mycocladus Beauverie (Ann. bniv. Lyon, 3: 1900). 

 Corresponding with Absidia in mycelial and sporangial char- 

 acters, but differing in that the suspensors of the zygospore lack 

 circinate outgrowths. 



The genus contains only the type species, M. verticellatus 

 Beau v., but species tentatively included in Absidia, in which 

 zygospores are as yet unknown, may later be found to belong here. 

 The genus is merged with Absidia by Lendner (1908 b: 129). 



5. Rhizopus Ehrenb. (Nova Acta Acad. Leopold., 10: 198, 1820). 

 Aerial arching stolons developed from the nutritive mycelium 



as in Absidia, at points of contact with the substratum forming 

 a tuft of repeatedly branched rhizoids (Fig. 82) ; sporangiophores 

 arising from the stolon exactly opposite the point of origin of the 

 rhizoids, usually unbranched and fasciculate; sporangia terminal, 

 large, globose, many-spored; columella prominent, more or less 

 hemispherical; sporangial wall not cutinized, at maturity almost 

 wholly disappearing; sporangiospores globose to oval or angular, 

 smooth or marked by longitudinal striations, rarely echinulate; 

 zygospores formed from the nutritive mycelium or from the 

 stolons; suspensors lacking outgrowths (Fig. 83). 



A rather large genus containing approximately thirty species 

 the best known of which is R. nigricans Ehrenberg, type of the 

 genus. In the papers of Pound (1894: 98), Wilson (1906: 560), 

 Sumstine (1910: 129), and Povah (1917: 248) the nomenclatorial 

 problem presented by this species is discussed. In the treatment 

 of Sumstine it is made the type of the genus Mucor, the name 



