40 ENDOSPOREAE [PHYSARUM 



The type of Didymium Curtiaii Berk, from South Carolina (B.M. 

 406) differs from typical B. rubiginosa only in being sessile or shortly 

 stalked. The type of B. siibaquila Macbr. from Maine (B.M. 3184) is 

 similar, but has completely sessile sporangia on a stout purplish 

 hypothallus ; in both British and American gatherings of B. rubiginosa, 

 however, the length of the stalk is subject to great variation, and the 

 sessile character alone would not appear to constitute a specific difference. 

 The typical form of the present species with minutely spinulose spores 

 is very abundant in the United States, but does not appear to be 

 common in Europe, and has not yet been obtained from the British 

 Isles. The var. dictyospora has been found several times in England 

 and Scotland, and also in Germany and Portugal. The var. globosa 

 has been obtained from various parts of England, from Wales, and 

 Ireland, always occurring on moss and ferns growing on wet rocks. 

 The resemblance which these gatherings bear to the unsatisfactory 

 type of Diderma Hookeri Berk. (K. 1559), from New Zealand, is very 

 striking. In the latter specimen the sporangia are studded over the 

 leaves of a species of Hymenophyllum, and were evidently much 

 weathered at the time of collection ; hardly any spores remain, and 

 even these may possibly have been introduced from external sources ; 

 the few slender bases of capillitium threads springing from the stout 

 columella strongly resemble those about the columella of B. rubiginosa 

 var. globosa, in some forms of which the capillitium is often very slender 

 and contains little or no lime. Although complete proof of the identity 

 of Diderma Hookeri and B. rubiginosa var. globosa cannot perhaps now 

 be obtained, the probability that they are the same form is strong. 

 (See Journ. Bot., xliii. 151, 1905.) 



Hab. In woods on fallen brushwood, etc. ; var. globosa on moss on 

 wet rocks.— Paris (B.M. 2105); Philadelphia (B.M. 1194); Maine 

 (B.M. 1587); Iowa (B.M. 815); South Carolina (B.M. 406): var. 

 dictyospora, Leighton, Beds (B.M. 1192) ; Appin, Argyllshire (K. 193) ; 

 North Germany (B.M. 2218) ; Portugal (B.M. 2085) : var. globosa, 

 Cheshire (B.M. 1036) ; North Wales (B.M. 1704) ; Galway (B.M. 2086). 



SPECIES REJECTED AND DOUBTFUL. 



Badhamia fulvescens Cooke is probably a fungus and to be 

 referred to the Perisporiacei, fide Dr. M. C. Cooke. 



B. irregularis Cooke & Ellis in Grev., v. 89 (1877), from New 

 Jersey, is described as having scattered sessile subglobose 

 or confluent sporangia, blackish-brown in colour, with 

 rough, blackish spores 10 fx diam. This account is too 

 brief for instruction. 



Genus 3.— PHYSARUM Persoonin Usteri Ann. Bot., xv. 5 

 (1795). Sporangia stalked, sessile, or forming plasmodio- 

 carps; sporangium-wall either single, or consisting of two 

 more or less separable layers, and containing minute rounded 

 lime-granuler distributed in loose or dense clusters or com- 

 pacted into a crust ; the lime always included and not in 

 superficial crystals. Stalk at first tubular (solid in P. 

 penetrate) ; the tube may become contracted and its 

 walls be wrinkled with longitudinal folds and translucent or 



