88 THE MYXOMYCETES 



69. Physarum gyrosum Rost. 



Mon. 111. 1875, in part. 

 PL VI, Figs. 123, 124. 



1892. Physarum cerebrinum Massee, Mon. 306. 



1902. Fuligo gyrosa (Rost.) Jahn, Ber. Deutsch. Bot. Ges. 20 : 272. 



Sporangia yellowish gray or pinkish gray, gyrose, irregular, often form- 

 ing dense, venulose, laterally compressed plasmodiocarps, sometimes 

 subaethalioid, usually sessile upon a common strongly developed hypo- 

 thallus; sometimes isolated and irregularly globose, or with a slender, 

 dull red stalk formed by a strand of the hypothallus; capillitium deli- 

 cate, the nodules elongate, variable in size; spores pale violaceous 

 brown, minutely spinulose, 7-10 /*. Plasmodium yellowish white. 



The present conception of this species is that of Jahn rather than 

 that of Rostafinski, although Jahn placed it in the genus Fuligo, to 

 which, indeed, it bears much resemblance. Rostafinski seems to have 

 included under this name not only the present species, but also 

 Fuligo muscorum and certain plasmodiocarpous phases of Physarella 

 oblonga. 



The species suggests a large, sessile form of Physarum polycephalum 

 but is distinct. 



Widespread, reported from every continent, but not very common 

 as a rule. In North America recorded from New York, Pennsylvania, 

 District of Columbia, Virginia, Mississippi, Iowa. 



70. Physarum polycephalum Schw. 



Schr. Naturforsch. Ges. Leipzig 1 : 63. 1822. 

 PL VI, Fig. 122. 



1829. Didymium polycephalum (Schw.) Fr., Syst. Myc. 3 : 122. 



1837. Didymium polymorphum Mont., Ann. Sc. Nat. 2 ser. 8 : 361. 



1837. Didymium gyrocephalum Mont., Ann. Sc. Nat. 2 ser. 8 : 362. 



1869. Didymium obrusseum Berk. & Curt., Jour. Linn. Soc. 10 : 348. 



1869. Didymium tenerrimum Berk. & Curt., Jour. Linn. Soc. 10 : 348. 



1875. Physarum polymorphum (Mont.) Rost., Mon. 107. 



1875. Tilmadoche gyrocephala (Mont.) Rost., Mon. 131. 



1876. Physarum obrusseum (Berk. & Curt.) Rost., Mon. App. 11. 

 1884. Physarum multiplex Pk., Bull. Torrey Bot. Club 11 : 50. 



1899. Tilmadoche polycephala (Schw.) Macbr. N. A. Slime-Moulds 57. 



Sporangia spherical or irregular, gyrose-confluent, helvelloid, um- 

 bilicate below; peridium thin, ashy, covered with evanescent yellow 

 squamules, fragile; stipe from an expanded membranaceous base, 

 long-subulate, yellow; spores minutely spinulose, violet, 9-11 /x. Plas- 

 modium yellow. 



A most singular and well-defined species, occurring in masses of 



