96 ENDOSPORE.E. [DIDYMIUM. 



3. D. Serpula Fries, Syst. Myc., iii., p. 126 (1829). Plasmodium 

 lemon-yellow, among dead leaves. Sporangia depressed effused plas- 

 modiocarps, 2 to 8 mm. broad, O'l to 0'15 mm. thick, or perforated 

 and net-like, or vermiform, grey ; sporangium-wall membranous, 

 colourless, with scattered superficial stellate crystals of lime. 

 Columella none. Capillitium of very slender, somewhat branching 

 and anastomosing, pale violet threads, connected with numerous 

 subglobose vesicles 20 to 50 ^ diam. filled with yellow, obscurely 

 granular matter. Spores pale violet-brown, minutely warted, 

 7 to 9 fj. diam. Host., Mon., App., p. 21. Lycoperdon compla- 

 natum Batsch, Elench. Fung., Cont. i., p. 251 (1786). Didymium 

 complanatum Host., Mon., p. 151 ; Cooke, Myx. Brit., p. 30. 



Plate XXXVIII., A. a. plasmodiocarp, x 2 ; I. section of the same, 

 showing the capillitinm and large vesicles, x 80 \ c. capillitium and spores, 

 x 280 ; d. spore, x 600 (England). 



The drawing of the capillitium in Mr. Massee's Monograph (fig. 56) 

 does not represent the characteristic vesicles of D. Serpula, and the 

 specimens from Kew, Batheaston, and Carlisle quoted by him (p. 234) 

 are plasmodiocarp forms of D. effusum, which D. Serpula superficially 

 resembles. These vesicles are frequently traversed by the capillitium 

 threads, and are apparently formed later ; they are minutely warted, 

 like the spores. 



Hob. On dead leaves. Lyme Regis (L:B.M.73) ; Freiburg, Ger- 

 many (L:B.M.73) ; Germany (B. M. 534, Strassb. Herb.) ; America 

 (L:B.M. 73). 



4. D. Clavus Host., Mon., p. 153 (1875). Plasmodium grey. 

 Total height 0'4 to O'Smm. Sporangium disc-shaped on a central 

 stalk, erect, scattered, 0'7 to 1 mm. diam., 0'2 mm. thick, greyish- 

 white ; sporangium -wall membranous, more or less spotted with 

 reddish-brown above, and beset with superficial clusters of stellate 

 crystals of lime, thicker and brown at the base. Stalk cylindrical, 

 longitudinally striate, pale brown or black. Columella none, 

 or represented only by the thickened base of the sporangium. 

 Capillitium profuse, of sparingly branched colourless or purple- 

 brown threads. Spores pale violet-brown, almost smooth, 6 to 8 

 /, diam. Cooke, Myx. Brit., p. 30; Mass., Mon., p. 230; Blytt, 

 Bidr. K. Norg., Sop. iii. (1892), p. 6. Physarum Clavus Alb. & 

 Schw., Consp. Fung., No. 267 (1805). Didymium melanopus ft 

 Clavus Fr., Syst. Myc., iii., p. 114. Didymium neglectum Mass., 

 Mon., p. 231. Didymium commutabile Berk. & Br., in Journ. 

 Linn. Soc., xiv., p. 83 ; Host., Mon., App., p. 21. Didymium 

 radiatum Mass., Mon., p. 229 (in part). 



Plate XXXVIII., B. a. sporangia, x 20 ; b. capillitium attached above 

 and below to the sporangium-walls, with spores, x 280; c. spore, x 600 

 (England). 



The characters of the type specimen of D. commutabile Berk. & Br. 

 (B. M. 537) agree in all respects with those of D. Clavus, except that 

 the stalk is 1*5 mm. long, and is encrusted with deposits of lime. The 

 type of D. neglectum Mass., from Philadelphia, growing with Physa- 

 rella mirabilis in Herb. Massee, is a slender form of D. Clavus : in all 



