THE GENUS DIPLODERMA. 



The genus Diploderma was based on the idea of a puff ball that 

 does not open, and we have decided to use the generic name, not- 

 withstanding that the original and most of the proposed species of 

 Diploderma are bulls. (Cfr. Myc. Notes, p. 181.) About a hundred 

 years ago Link proposed the genus Diploderma, basing it on an un- 

 opened specimen of Geaster hygrometricus, still preserved at Berlin. 

 Seven species from Australia and one from Hungary have since been 

 added, most of which are unopened Geasters. 



It was Cooke, in his Australian Handbook, who brought the 

 "genus" into prominence and disrepute. He defines it as having a 

 "central, woody nucleus," which definition belongs to Mesophellia 

 (see previous genus), not to Diploderma, and then as evidence of 

 the care that Cooke bestowed on his work, after so defining the genus, 

 two-thirds of the "species" he includes do not have "central, woody 

 cores." He includes six species; two are Mesophellias, two are un- 

 opened Geasters, and two, D. suberosum and D. album, are imma- 

 ture, but probably good species of something, if they were adequately 

 known. Both have globose spores, but otherwise appear as though 

 they may be cogeneric with Diploderma avellaneum. 



The genus, excluding the Mesophellias and unopened Geasters 

 that do not belong to it, could be defined as follows : 



Peridium double, the inner usually hard and rigid. Dehis- 

 cence none, or at least unknown. Sterile base or central core none. 

 Capillitium hyaline. Spores elliptical or globose, very pale color or 

 hyaline. 



This genus, only known from Australasia, is close to Meso- 

 phellia, differing in having no central core. 



DIPLODERMA AVELLANEUM, FROM C. C. BRITTLE- 

 BANK, AUSTRALIA (Fig. 913). Peridium 1 to 2 cm. injdiameter, 

 globose, about the size 

 and color of a hazel nut. 

 Outer peridium thin, 

 closely adnate. Inner 

 peridium thick, hard, 

 woody, white. Gleba 

 pale buff color (near 

 chamois ; R i d g w a y ) . 

 Columella or core, none. 

 Capillitium scanty, cob- Fig. 913 



webby, hyaline. Spores 

 elliptical, 5-6 x 8-12, pale ochraceous, subhyaline, minutely warty. 



Two specimens (Fig. 913) were received from Mr. Brittlebank 

 (No. 2). Neither shows any signs of dehiscence. 



DIPLODERMA INSOLITUM, FROM C. C. BRITTLEBANK, 

 AUSTRALIA (Fig. 914). Plant 2-3 cm. in diameter, without root- 

 ing base. Exoperidium thin, but rigid, pale. Gleba filling the peridium, 

 pale, rosy color. Capillitium cobwebby, of hyaline, flaccid threads. 

 Spores varying 7-8x12-16, elliptical, pale, subhyaline, minutely 



641 



