20 THE NORTH AMERICAN SLIME-MOULDS 



SUB-CLASS MYXOGASTRES (Fries) Macbr. 

 Myxomycetes proper. 



1829. Sub-order Myxogastres Fries, Syst. Myc., III., p. 67. 



1833. Sub-order Myxomycetes Link, Handb. der Geiv., 3, p. 405. 



1833. Sub-order Myxomycetes Wallroth, Fl. Crypt., II., p. 333 (in part). 



1858. Class Mycetozoa De Bary. Bot. Zeitung, 1858, pp. 357-365 (in part). 



1889. Class Myxogastres Schroeter, Engl. . Prantl Nat. Pflanz., I. i., 

 p. 16. 



1892. Class Myxogastres (Fries) Massee, Monograph, p. 28. 



1894. Class Mycetozoa Lister, Mycetozoa, p. 21. 



Saprophytic Slime-moulds. So far as known the spores in 

 germination give rise to zoospores, at first amoeboid, later ciliate, 

 which are capable of continued independent existence, increase 

 by fission, and finally coalesce to form the plasmodial phase. 

 The fruiting phase presents abundant minute unicellular spores, 

 which are enclosed in sporangia more or less perfectly defined, 

 and are more frequently attended by peculiar thread-like struc- 

 tures, formed from residual spore-plasm, the capillitium. 



Key to the Orders of the Myxogastres. 



Spore-mass black or violaceous, rarely ferruginous . . . SERIES A 



Spore-mass never black, usually some shade of brown or yellow, rarely 



purplish or rosy, etc. SERIES B 



SERIES A. 



1. Capillitium present, delicate, thread-like; sporangia calcareous, more or 



less throughout I. PHYSARACE^E 



2. Capillitium present, thread-like, arising usually as anastomosing branches 



from a well-developed columella, which in a single genus contains 

 lime; sporangia otherwise non-calcareous . II. STEMONITACE^E 



SERIES B. 



3. Capillitium none, or very imperfectly developed; spores of some shade 



of brown, rarely purplish . . . . III. CRIBRARIACE/E 



4. Capillitium the inwardly produced irregular extremities of plates or 



tubules, which by their interweaving outwardly make up the aethalial 

 wall ; spores pale, ashen .... IV. LYCOGALACE^E 



5. Capillitium made up of more or less distinctly sculptured threads, parie- 



tal or free ; spores commonly yellow . . .V. TRICHIACE^E 



