52 THE NORTH AMERICAN SLIME-MOULDS 



above into a shallow cup-like base for the sporangium ; colu- 

 mella none ; capillitium with lime knots more or less abundant, 

 white, often uniting, Bad/iamia-liko. ; spore-mass black ; spores 

 by transmitted light, pale lilac brown, almost smooth, 10-12 p. 



One of the smallest species of the genus, by its proportion- 

 ally long stipe and small round sporangium reminding one 

 somewhat of P. globulifcrum. Much smaller, however, and in 

 every way different. The generic characters are mixed, and 

 the species has been accordingly variously referred. The lower 

 part of the peridium is sometimes persistent after the dehiscence, 

 and so far reminds of Craterinm. But this character is not 

 constant, and the persisting part is very small, not greater than 

 in P. mcllcmn, for example. On the other hand, the capilli- 

 tium in some sporangia is strongly calcareous, almost as in Bad- 

 Jiamia, but in most sporangia the Physarum characters are 

 sufficiently clear. 



South Carolina, Florida. 



32. PHYSARUM OBRUSSEUM (Berk, and Curt?) Rost. 



1869. Didymhun obrusseum Berk and Curt., Jour. Linn. Soc., X., p. 348. 



1869. Didymium tenerrimum Berk and Curt., I.e. 



1875. Physarum obrusseum Berk and Curt., Rost., Mon. App., p. n. 



1890. Physarum tenerum Rex., Proc. Phil. Acad., p. 192. 



1894. Physarum polymorphism Rost. var. obrusseum, Lister, Myc., p. 48. 



Sporangia scattered, small, \ mm., stipitate, erect or nodding ; 

 the peridium thin, membranaceous, thickly studded with circular, 

 flattened yellow granules of lime ; stipe long, slender, subulate, 

 opaque, pale brown, striate below, pale yellow above ; columella 

 none ; capillitium white, delicate, forming a loosely but regu- 

 larly meshed network with numerous small round or rounded 

 granules at the intersections ; spores dark brown, delicately 

 warted, 7.5-8 /z. 



This delicate Physarum* very fragile and evanescent, seems 

 to be distinct by reason of its characteristic rounded lime gran- 

 ules from any similar stipitate species. It varies a little accord- 

 ing to locality. Ohio specimens are a little larger and have 



