202 THE MYXOMYCETES 



large-meshed network; spore-mass black; spores by transmitted light 

 smoky brown, rough, 11-14 jj,. Plasmodium white, rarely yellow. 



Rostafinski distinguished this beautiful species by the color of the 

 peridium and the conic columella. According to Mr. Lister, Rostafin- 

 ski was not sufficiently careful in labelling his material, different forms 

 having been included under this specific name. Nevertheless, the 

 description is well drawn, and excludes L. physaroides completely. At 

 all events our American specimens correspond so well with the de- 

 scription of L. columbinum (Pers.) Rost. that there seems no doubt 

 that we have here what the Polish author figured and described, 

 whether or not he was always consistent in applying his labels. The 

 color distinguishes at sight the present species from L. physaroides, 

 and the capillitium and large rough brown spores distinguish it from 

 L. violaceum. The capillitium of the minute L. scintillans is much 

 denser and more rigid, and the spores smaller. The stipe when dry is 

 ciliate. 



This is the common species of our western mountains, especially on 

 the Pacific slope. In the Cascades every dark ravine is certain to show 

 it in later summer and autumn, far extended colonies covering the moist 

 surfaces of every moldering log, the myriad globoid sporangia giving 

 back when brought to the sunlight the most extravagant blues and 

 greens with all the splendor of metallic sheen. Their brilliant beauty 

 never fails to quicken the attention of even the most insensate tourist. 



The English monograph recognizes the varieties gracile G. List., 

 with elongated oval sporangia; iridescens G. List. (= Physarum 

 iridescens Berk., Hooker Jour. Bot. 3 : 20, 1851; L. iridescens (Berk.) 

 Rost., Mon. App. 25, 1876), with spherical sporangia and pale, lax 

 capillitium, and brevipes G. List., with dull, flattened sporangia and 

 very short stalks. Meylan (Bull. Soc. Vaud. Sc. Nat. 56 : 322, 1927) 

 believes brevipes a distinct species, and in the same publication raises 

 his former variety subglobosum to specific rank as L. subglobosum. This 

 has a slightly flattened sporangium, like brevipes, but a long stalk and 

 a short columella. L. cruchetii Meylan is not regarded by Miss Lister 

 as worthy even of varietal recognition. According to Meylan it has a 

 yellow Plasmodium requiring two or three weeks to form sporangia, 

 while that of L. columbinum is white and forms sporangia in two to 

 four days after emergence. There are other differences cited, such as 

 the proportionately shorter stem of cruchetii, its somewhat simpler 

 capillitium, and its somewhat larger, often greenish brown spores. 

 These forms are as yet known only from the Swiss mountains, but will 

 doubtless appear elsewhere. 



Abundant in the western forests, extremely rare in the eastern 



