DIDYMIUM.] DIDYMIACE.*:. 101 



lime deposits ; the spores in the Strassburg specimen are minutely 

 roughened with warts on the hemisphere of the usual- number observed 

 in D. effusum ; the points of difference are that in the Strassburg 

 specimen the sporangia are subglobose or of irregular shape, on a 

 broad base, the sporangium- wall crumpled and whitish ; in the Lyme 

 Regis specimen the sporangium is a depressed plasmodiocarp, and 

 resembles a Lamproderma in the iridescent wall ; but it is associated 

 with other sporangia scantily furnished with lime, and also with those 

 of the usual form. Chondrioderma Cookei Rost., of which the gathering 

 by Mr. Th. Brittain is represented in Strassb. Herb, and Brit. Mus. 

 (B. M. 137), appears to be another form of D. effusum, differing 

 from the type with sessile sporangia in the absence of lime except in 

 minute spicules scattered over the sporangium-wall ; the capillitium 

 is an irregular network of dull violet threads, with expansions con- 

 taining nodules of lime such as are of frequent occurrence in imperfect 

 developments both in this species and its allies ; the spores are spinulose, 

 10 to 12 p, diam. 



Hob. On dead leaves, etc. ; common. Lyme Regis, Dorset (L:B.M. 

 77) ; Batheaston, Somerset (B. M. 37) ; Sydenham, Surrey (B. M. 1070) ; 

 Welshpool, Montgomery (B. M.) ; France (K. 12) ; Germany (B. M. 

 530, 550) ; Austria (B. M. 567) ; Italy (B. M. 433) ; Ceylon (B. M. 456) ; 

 New Zealand (K. 1324) ; Philadelphia (L;B.M.77); S. Carolina (K. 89); 

 Cuba (K. 542) ; Chili (Paris Herb.) ; Paraguay (Paris Herb.). 



8. D. crustaceum Fries, Syst. Myc., iii., p. 124 (1829). 

 Plasmodium white, .among dead leaves. Sporangia at first globose, 

 confluent, aggregated or scattered, shortly stipitate or sessile, 0'7 

 to 2 mm. diam., smooth and white from the thick fragile deci- 

 duous crust of loosely compacted crystals of lime in which they 

 are enclosed; when the crust has fallen away the sporangia are 

 seen to be grey, and reniform or hemispherical ; sporangium- 

 wall i membra nous, colourless, clothed with large stellate crystals 

 of lime. Stalks pale buff, 0'2 to 0'4 mm. high, membranous, 

 eight or ten often clustered together on an expansion of the 

 membranous hypothallus, at first concealed under the crust of 

 lirne enclosing the sporangia. Columella small, irregular, de- 

 pressed, or not evident in the sessile forms, white or pale buff, 

 charged with coarse granules of lime. Capillitium of colourless 

 or pale violet branching threads 4 5 to 1 //. diam., with numerous 

 minute fusiform thickenings. Spores purplish-grey, strongly 

 spinulose, 10 to 13 /x, diam. Rost., Mon., App., p. 22. D. confluens 

 Rost., Mon., p. 164 (non Rost., Mon., App., p. 22) ; Mass,, Mon., 

 p. 235. 



Plate XL., B. a. sporangia, x 20 ; b. cluster of sporangia from which 

 the outer crust of lime has fallen away, arising from a common hypothallus, 

 x 20 ; c. capillitium and spores, x 280; d. crystals of lime from the 

 sporangium-wall, x 280 ; e. spore, x 600 (England). 



Closely allied to D. effusum, differing chiefly in the deciduous 

 calcareous envelope of the sporangia, which is often 0'25 mm. thick, 

 and in the membranous stalks. It forms a connecting link between 

 D. effusum and Spujnaria alba. 



Hab. On dead leaves, etc. Lyme Regis, Dorset (L:B.M. 78) ; Poland 

 (Strassb. Herb.). 



