88 THE NORTH AMERICAN SLIME-MOULDS 



present species ; the stipe is more abundantly and deeply plicate, 

 is sometimes tinged with brown, and the capillitium is darker 

 colored and coarser than in what is here regarded as the type 

 of the species ; but withal the specimens certainly fail to meet 

 the requirements of Rostafinski's elaborate description and 

 figure (Mon., p. 161 and Fig. 154). 



D. cffuswu Link, probably stands for a sessile form of this 

 species, but Link's brief description (1816) is antedated by the 

 much better one of Albertini and Schweinitz, I.e. 



Generally distributed throughout the wooded regions of North 

 America, from New England to Nicaragua, and from Canada 

 to California. Not uncommon about stable-manure heaps, in 

 flower beds, and on richly manured lands. July, August. 



Nicaragua specimens not only show a continuous vein-like 

 hypothallus, but have the peridia often confluent, the columellas 

 in such cases confluent, the stipes distinct. Furthermore, the 

 largest spores reach the limit of 12.5 /A, and perhaps the larger 

 number range from 10-12.5 A 1 * an d all are very rough. This 

 corresponds with D. macrospcrmum Rost., which is distinguished, 

 says the author (Mon., p. 162, opis\ "chiefly by the large and 

 strongly spinulose spores." However, the same sporangium in 

 our Central American specimens yields spores 7.5-12.5 /*. So 

 that D. inacrospcnmnn on this side the ocean, at least, cannot 

 be distinguished from D. squamulosum, as far as spores are 

 concerned. A similar remark may be made relative to the form 

 of the columella which Rostafinski, in his figures especially, 

 would make diagnostic. The columella in the sporangia with 

 largest and roughest spores is that of a perfectly normal 

 D. sqnamulosum. 



5- DlDYMIUM MELANOSPERMUM (Pd'S^) Mticbr. 



PLATE VII., Figs. 3, 3 a. 



1794. Physarnm melanospermum Pers., Rom. N. Mag. Bot., p. 89. 

 1797. Didymium farinaceum Schrader, Nov. Gen. PL, p. 26, t. 5, Fig. 6. 



Sporangia gregarious, hemispheric, depressed, umbilicate 

 below, stipitate or sessile ; the peridium firm, dull brown in 



