192 THE MYXOMYCETES 



6. Lamproderma Rost. 



Versuch 7. 1873. 

 Sporangia stipitate, rarely sessile, globose or ellipsoid ; columella 

 cylindric or sometimes clavate, scarcely attaining half the height of 

 the peridium; peridium shining with metallic tints, deciduous, except 

 where, at the base of the columella, it forms a ring around the stipe; 

 capillitium rising in tufts or by simple branches mainly from the tip 

 of the columella, the threads regularly forked, generally united into 



a net. 



The lamprodermas are distinguished from the comatrichas, to which 

 they are most nearly allied, by the arrangement of the capillitium, 

 its development largely from the apex of the columella, the continua- 

 tion of the stipe within the peridium. In other words, the peridium 

 leaves the stipe some distance below the point where the lowest capil- 

 litial branches take origin. In mature specimens the peridium has 

 often entirely disappeared, its only trace a more or less distinct collar 

 around the stipe marking the beginning of the columella. Neverthe- 

 less the peridium is far more persistent than in any comatricha, and 

 shows in yet greater brilliancy the wondrous metallic tints and iri- 

 descence of Comatricha and Diachea. Older authors, so far as can be 

 seen, distributed the species between Physarum and Stemonitis. 



Meylan, who has devoted much attention to the genus and has 

 described a number of new species, is of the opinion that many of 

 the older names have been used to designate what are in reality ag- 

 gregates of several species which must eventually be recognized. The 

 difficulties in the way of deciding which are constant characters and 

 which are variations induced by changes in the environment are so 

 great, however, that it seems wise to be conservative in recognizing 

 newly proposed forms. Meylan 's species are therefore mentioned in 

 connection with the forms within which they would seem to be included 

 according to older usage. 



KEY TO THE SPECIES OF LAMPRODERMA 



a. Spores reticulated or marked with raised bands or lines of 



warts " 



a. Spores warted, spinulose or nearly smooth • • • d 



b. Reticulation complete, regular 1. L. cribrarioides 



b. Reticulation incomplete or replaced by lines c 



c. Peridium thin, membranous, dark gray; spores covered 



with warted vesicles, the warts in lines or circles 2. L. cristatum 



c. Peridium somewhat thicker, fragile, dull; spores incom- 

 pletely reticulate with lines of warts 3. L. atrosporum 



d. Spores coarsely echinulate, 14-20 n e 



d. Spores finely warted or echinulate, usually under 15 /z i 



