1 10 ENDOSPOREAE [DIDERMA 



Hab. On moss and liverworts on wet rocks. — North Wales (B.M. 

 2417) ; Japan (B.M. 2418) ; Massachusetts (B.M. slide). 



11. D. Trevelyani Fr. Syst. Myc, iii. 105 (1829). Plas- 

 modium ? Sporangia scattered or clustered, globose or sub- 

 ellipsoid, 1 to 1-5 mm. diam., sessile or shortly stalked, rarely 

 forming plasmodiocarps, verrucose or nearly smooth, reddish 

 or orange-brown ; sporangium-wall either splitting irregularly 

 or in unequal revolute petal-like lobes, white and glossy on 

 the inner side : of three closely connected layers, the outer 

 one cartilaginous, brown ; the inner delicately membranous, 

 giving attachment to the threads of the capillitium ; the 

 middle layer thick, composed of coarse irregular crystals of 

 lime. Stalk furrowed, reddish-brown, 0-1 to 0-5 mm. high, 

 0-1 to 0*15 mm. thick. Columella subglobose, either minute, 

 or more rarely large, but most frequently entirely absent. 

 Capillitium profuse, purple or purplish-brown, somewhat 

 rigid, either forming a network with dark bead-like thicken- 

 ings at the nodes and on the threads, or slender, branched, 

 with few thickenings. Spores dark violet-brown, spinulose, 

 10 to 13 [x diam. — Macbr. N. Am. Slime-Moulds, 102. Lean- 

 gium Trevelyani Grev. Scot. Crypt. Fl., tab. 132 (1825). 

 Chondrioderma Trevelyani Rost. Mon., p. 182 (1875) ; Mass. 

 Mon., 202 ; Lister Mycetozoa, 82. C. Oerstedtii Rost. I.e., 

 p. 184, figs. 154, 157 ; Mass. I.e., 203. C. geasteroides Phill. 

 in Mass., I.e., 201 (1892). Diderma geasteroides Phill. in 

 Grev., v. 113 (1877). D. laciniatum Phill., I.e. Lepidoderma 

 obovatum Mass., I.e., 254 ? 



PI. 91. — a. expanded sporangia (California ; type of D. geasteroides) ; 6. entire 

 sporangia (England) ; c. capillitium and spores with fragment of sporangium wall ; 

 d. spore. 



The crystalline middle layer of the sporangium-wall separates this 

 from all other species of the Leangium group. The type of D. Trevelyani 

 described and figured under the name of Leangium Trevelyani Grev., 

 is in the Edinburgh Herbarium ; the sporangia are sessile on Mnium 

 undulatum, and were gathered by W. C. Trevelyan, Esq., who also sent 

 a specimen to Mr. Sowerby ; the gathering named Diderma Trevelyani, 

 " Sowerby Herb." (K. 1478), also on Mnium undulatum, is no doubt 

 the specimen referred to. Greville speaks of and figures a " very 

 minute columella " ; Berkeley in describing Trevelyan's gathering 

 states : " I find no trace of a columella ; the bottom of the peridium 

 within is perfectly even." Examination of the type in the Edinburgh 

 collection confirms Berkeley's statement as far as the sporangia now 

 remaining are concerned. That Greville was in all probability correct 

 with regard to other sporangia of the gathering may be inferred from 

 the variety seen in extensive developments found amongst grass on the 

 upper pastures of the Swiss Alps ; most of these sporangia are of the 

 usual character having a smooth pearly basal inner wall and showing no 

 trace of columella, others have a small, often eccentric columella, while 

 others again have a large subglobose columella. Associated with normal 

 sporangia broad plate-like plasmodiocarps sometimes occur. The 



