134 Natural History Bulletin. 



tips, spinescent throughout. Spiral bands distinct, about 

 three. Spores smooth, .010-.012. 



Our most common Slime-mould, found on rotten wood and 

 bark of all sorts from June to September, easily recognized 

 by the color. Several varieties are recognized, of which 

 genuina, stalked, as described, alone occurs here. All author- 

 ities agree in describing European specimens with "spores 

 smooth." I have not had opportunity to examine with the 

 microscope European material, but a most careful observer 

 who has so done reports that the spores of specimens sent 

 him from Europe are not smooth. The material distributed 

 in the N. A. F. No. 1113, agrees with our Iowa material in 

 having the spores minutely verruculose. On the fact of rough 

 spores, Massee founds the species U. ellisii. (Jour. Roy. 

 Mic. Soc, 1889, p. 354). If then Massee's point were well 

 taken, our species must be called hereafter H. elltsii, Mass. 



29. Hemiarcyria clavata, Pe7'soon. Plate V, Figs. 2, 2a 

 and 25, and Plate III, Figs. 6, 612 and 6b. 



Sporangia single, gregarious, spherical or obclavate. Peri- 

 dium thin, bright, shining, yellow. Stipe generally of a darker 

 hue, brown or reddish. Spore-mass and capillitium yellow or 

 ochraceous. Capillitium repeatedly branching, with abundant 

 free, rounded ends, the tubes adorned with several spiral 

 bands. Spores minutely warted, .008-.009. 



Very common, occurring with the preceding, the plasmodia 

 of the two species being often strangely intermingled on the 

 same substratum. Under a good lens (Leitz Jg^) the capillitial 

 threads show themselves minutely warted. The specimen 

 distributed by N. A. F., 536, shows the same peculiarity. 

 Authorities generally ignore the fact, or say " smooth." 



The figures of Plate III, illustrate a very delicate variation 

 of the present species. The sporangia are much smaller, 

 borne on proportionately longer stipes. The capillitium is less 



