248 THE NORTH AMERICAN SLIME-MOULDS 



i. Dusky. 



* Long, 12 mm. or more .... I. A. magna 

 ** Shorter, about 6 mm 2. A. oerstedtii 



ii. Yellow "i. A. nutans 



b. Mature capillitium short, not drooping, though sometimes pro- 

 cumbent, 

 i. Capillitium greenish yellow . . . . A-. A. versicolor 

 ii. Capillitium reddish, flesh-colored, at length sordid, etc. 



* Capillitium marked by transverse half-rings, cogs, etc. 



5. A. incarnata 



** Capillitium marked by sharp-edged transverse plates and 



by numerous nodes . . . . 6. A, nodulosa 



*** Capillitium marked by close reticulations, 7. A. ferruginea 



B. Capillitium persistently attached to the calyculus. 



a. Sporangia reddish brown, etc i. A. denudata 



b. Sporangia gray or ashen 



i Simple 9. A. cinerea 



ii. Clustered 10. A. digitata 



c. Sporangia yellow II. A, pomiformis 



d. Sporangia rose-colored, .5-1.5 mm. ... 12. A. insignis 



1. Arcyria magna Rex. 

 1893. Arcyria magna Rex, Proc. Phil. Acad., p. 364. 



Sporangia densely aggregated, forming clusters of greater or less 

 extent, sometimes reaching several centimetres in either direction, 

 tawny gray or ashen, cylindric, tapering a little above, when expand- 

 ed reaching a length of half a centimetre or more, stipitate ; peridium 

 evanescent except the small shallow cup-like base, the calyculus ; stipe 

 long (1 mm.), weak, pale brown or reddish, tubular, the channel 

 filled with plasmodic masses; capillitium gray or drab-colored, very 

 slightly attached to the bottom of the calyculus, far expanded, form- 

 ing a loose-meshed net, the threads regular, cylindric, coarsely sculp- 

 tured with rings, half-rings, cogs, spines, etc.; spores in mass dull 

 gray, drab, under the lens colorless, papillate, with few papillae, 

 7-8/*. 



This magnificent form resembles in habit and general appearance, 

 save color, A. nutans. The capillitium is, however, very diflferent 

 both in the sculpture and in the more delicate markings of the threads. 

 Dr. Rex, /. c, has pointed out the lack of reticulation on the cap- 

 illitium and calyculus. The color is also diagnostic. A roseate vari- 



