190 



THE NORTH AMERICAN SLIME-MOULDS 



i. Capillitium yellow 4. A. vitellina 



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 8. A. denudata 



b. Sporangia gray or ashen. 



i. Simple 9. A. cinerea 



ii. Clustered 10. A. digitata 



c. Sporangia yellow ii. A . pomiformis 



i. 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 expanded reaching a length of half a centimetre or more 

 stipitate ; peridium evanescent except the small shallow cup- 

 like base, the calyculus; stipe long (i 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, forming a loose-meshed 

 net, the threads regular, cylindric, coarsely sculptured 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 appear- 

 ance, save color, A. nntans. The Capillitium is, however, very 

 different both in the sculpture and in the more delicate mark- 

 ings of the threads. Dr. Rex, I.e., has pointed out the lack of 

 reticulation on the Capillitium and the calyculus. The color is 

 also diagnostic. A roseate variety seems to occur with the 

 present form. This is A. magna rosea Rex, and appears to 

 agree with the type in all respects save color. The relationship 

 here must be determined by future inquiry. The capillitial 



