Sumstine: North American Mucorales 139 



ce que chez les Piloholus; mais il n'est pas projete dans I'atmos- 

 phere, et a cette absence de projection correspond naturellement 

 Tabsence de la structure et de la forme si caracteristiques du fila- 

 ment sporangifere qui determinent ce phenomene les Piloholus. 

 . . . C'est de cette faculte de soulever son sporange au lieu de 

 le projeter que j'ai tire le nom generique Pilaira, par opposition 

 a celui de Piloholus. 



Type species, Pilaira Cesatii Van TiQghQm = Piloholus anoma- 

 lus Cesati. 



This genus is chiefly distinguished from Hydrogera by the 

 absence of mycelial and subsporangial swellings. 



Fischer (Rabenh. Krypt. Fl. i*: 257) cites Hydrophora tenella 

 Tode as a synonym of Pilaira nigrescens Van Tieghem. If the 

 synonymy of these two species could be established, then the genus 

 Pilaira would become a synonym of Hydrophora with H. tenella 

 as the type of the latter genus. This would change the concep- 

 tion of the genus Hydrophora. The lack of type specimens and 

 the very brief diagnosis of Hydrophora tenella do not justify 

 such a conclusion. The genus of Van Tieghem therefore stands. 



I. Pilaira fimetaria (Link) Pound, Minn. Bot. Studies i: 100. 



1894 



Mucor fimetarius Link, Ges. Naturf . Freunde Berl. Mag. 3 : 30. 



1809. Berl. Mag. Gesell. Naturf. Freunde. 

 Piloholus anomalus Cesati, Bot. Zeit. 9: 647. 1851. 

 Hydrophora fimetaria Fries, Syst. Myc. 3: 313. 1829. 

 Ascophora Cesatii Coemans, Acad. Roy. Sci. Belg. 30: 63. 1861. 

 Pilaira Cesatii Van Tieghem, Ann. Sci. Nat. VL 1:51. 1875. 



Link's name is evidently the oldest that can with any certainty 

 be applied to this species. 



The sporangia are black when mature, columella depressed 

 globose, spores oval or elliptic oval. The zygospores are borne 

 on tongue-shaped copulating branches. 



Substrata: On decoction of manure. 



Specimens examined: Pennsylvania, Sumstine. (In labora- 

 tory cultures.) 



Illustrations: Van Tieghem, /. c. pi. i, f. 14-24; Coemans, 

 I. c. pi. 2, f. e. 



