50 THE MYXOMYCETES 



Sporangia small, 0.2-0.4 mm. in diameter, or rarely larger, sessile, 

 often crowded or heaped in small bunches, a dozen or more sporangia 

 in one pile, spherical, ovoid or elongate, yellow or greenish yellow or 

 pallid gray-green; peridium thin, fragile; capillitium delicate, with 

 rather small, irregular, yellowish, calcareous nodes; columella none; 

 spores bright violet, minutely roughened, 7-10 ix. 



This species occurs most commonly on moss-tufts, with which it is 

 frequently concolorous, or escaped on dead leaves, etc. The peridium 

 is flecked with calcareous scales or grains stained yellow or green, and 

 to these the whole fruit owes its peculiar color. The color and aggregate, 

 heaped sporangia are distinctive macroscopic characters. 



In the Monograph, p. 103, Rostafinski properly adopted Ditmar's 

 name for this species. Upon later consideration, in the Appendix, he 

 changed the name, writing P. ditmari, on the ground that virescens 

 was descriptive of a character to which it occasionally refuses to 

 conform. Most authors since Rostafinski have simply accepted his 

 suggestion, so that the species is often entered as P. ditmari Rost. 

 P. virescens is certainly to be preferred. 



Var. obscurum List, is greenish gray, larger, with spores 6-8 /z; var. 

 nitens List, is bright yellow or orange. 



Widely distributed in Canada, the United States and Europe; also 

 Java, Japan. 



10. Physarum lateritium {Berk. &" Rav.) Morg. 

 Jour. Cin. Soc. Nat. Hist. 19 : 23. 1896. 



1873. Didymium lateritium Berk. & Rav., Grev. 2 : 65. 



1873. Didymium croceoflavum Berk. & Br., Jour. Linn. Soc. 14 : 84. 



1876. Physarum ditmari var. croceoflavum Rost., Mon. App. 9. 



1876. Physarum ditmari var. lateritium Rost., Mon. App. 9. 



1879. Physarum inccquale Peck, Rept. N. Y. State Mus. 31 : 40. 



1892. Physarum chrysotrichum Berk. & Curt, ex Massee, Mon. 300, in part. 



Sporangia gregarious, sessile, globose, subglobose or plasmodio- 

 carpous, yellowish or orange when fresh, spotted with minute scarlet 

 granules; peridium thin, more or less rugulose; columella none; cap- 

 illitium delicate, the colorless or yellow threads connecting the yellow 

 nodules, these often with red centers; spores violet-brown in mass, 

 by transmitted light pale violet, minutely roughened, 7-9 lx. 



A well-marked species easily recognized by the characters cited. 

 The extent of lime deposit at the capillitial nodes varies; it is some- 

 times very scanty. This acounts for Berkeley's generic reference. 

 The capillitium in broken specimens soon fades, becoming pallid or 

 whitish. 



