The Myxomycetes of the Miatni J'al/ey, Ohio. 139 



(Growing on old wood, ^^vthalium somewhat circular, or 

 often quite irregular in shape, i to several centimeters in 

 extent, the individual sporangia nearly i mm. in height, but 

 scarcely .1 mm. in thickness. Deviations from the typical 

 form of the sporangia sometimes occur, they are not seldom 

 pentangular, and I have seen the apices quadrangular, with 

 only four threads, or even triangular, and with but three ; the 

 threads, too, are said occasionally to branch and anastomose. 

 Rcticularia plumbea, Fries, S. M. Ill, 88; and Ostracoderma 

 spadkeum, Schw., N. A. Fungi No. 2,381. 



III. CRIBRARIA, Pers. Sporangia simple, globose or obo- 

 void, stipitate, often cernuous ; the wall regularly thickened 

 on the inner surface in two ways, the lower basal portion by 

 radiating ribs consisting of minute brown granules, the upper 

 part by slender threads combined into a network of polygonal 

 meshes ; the basal portion of the membrane is commonly per- 

 sistent with its thickening and is called the calycidns, the 

 upper part nearly always disappears from the network at 

 maturity ; there are usually nodules of the brown granules at 

 the angles of the network. Spores globose, purple, brown, 

 ochraceous. 



a. Sporangium, large. 



I. Cribr.vria argillacea, Pers. Sporangia globose or 

 obovoid, stipitate or nearly sessile, standing close together on 

 a thin and evanescent hypothallus; the wall quite firm, 

 silvery-shining, the greater portion persistent, breaking awaj' 

 about the apex ; calyculus small, the brown radiating ribs 

 soon passing into a network of polygonal meshes, the threads 

 with irregular granulose-thickened portions at intervals 

 throughout their whole extent. Stipe very short, erect, 

 brown. •Spores in the mass argillaceous, globose, 5-7 niic. in 

 diameter. 



Growing in large irregular patches on rotten trunks. Spor- 

 angia .6-. 8 mm. in diameter, the stipe always much shorter 

 than the sporangium, sometimes nearly obsolete. The resem- 

 blance of this species to some forms of Tiibiilina ceespitosa is 

 verv great. 



