162 NOTES ON MYCETOZOA. 



P. Uvidiim, in bis Monograph, p. 95, is as follows : — '' Sporangia 

 irregularly shaped, hemispherical, depressed, sessile, greyish white 

 or white ; colnmella none, or a central mass formed from the 

 capillitium ; capillitium with numerous roundish snow-white lime- 

 kiiots ; spores violet-black, with a thick strongly spinulose mem- 

 brane." He then gives var. Ucheniformis " with the sporangia 

 seated on a strongly developed hypothallus," quoting a gathermg 

 from Bethlehem, S. Carolina, and var. couglobatum " without hypo- 

 thallus." The essential points of difference between P. didermoides 

 and P. lividum resolve themselves into the shape of the sporangia, 

 and the presence or absence of a stalk. As indicating the difficulty 

 Rostafinski felt in this distinction, he has marked a specimen from 

 Ceylon (No. 135, Kew Coll.), which has sessile irregularly-shaped 

 sporangia, as F. didermoides. In both English and American 

 specimens of undoubted P. didermoides we meet with both ellipsoid 

 and irregularly-shaped sporangia and stalked and sessile sporangia 

 in the same development ; the characters which distinguish P. 

 lividum seem therefore to fall to the ground. At the same time the 

 extreme forms represented by gatherings in which no sessile spor- 

 angia occur and those in which no stalked sporangia occur (as is 

 the case with the Chaul End specimens) should be recorded as 

 varieties, and I mark the latter as P. didermoides var. lividum. The 

 type of P. lividum. var. licheniforme Rost. referred to above, is in 

 Nees's herbarium at Strassburg, and was collected by Schweinitz at 

 Bethlehem, S. Carolina ; the subglobose sporangia are seated on a 

 white hypothallus. I have given it as a sessile form of P. dider- 

 moides in Brit. Mus. Cat. Myc. p. 55. There is a specimen from 

 Mr. F. L. Harvey, Orono, Maine, in the Brit. Mus. Coll. (B. M. 

 1595) which I mark P. didermoides var. lividum; the sporangia are 

 globose ; it is the only example of the species we have met with in 

 which the spores are identical with those of the gatherings from 

 Chaul End. The unequal thickness of the spore-wall seems, how- 

 ever, to be too inconstant to be an important character. 



Physarum didermoides Rost. On Oct. 19th, 1897, I received a 

 good supply of this species from a large growth found on a heap of 

 stable manure by Mr. C. Crouch at Mead Hook Farm, near Pullox- 

 hill, Beds. The greater part is a fairly typical form with erect 

 ellipsoid sporangia on white membranous stalks ; a considerable 

 portion, however, consists of irregularly globose sessile sporangia 

 seated on a white hypothallus ; the capillitium is of the normal 

 form, with small rounded lime-knots connected by slender flexuose 

 sparingly branched hyaline threads, and frequently with a large cen- 

 tral mass of lime composed of confluent lime-knots ; the spores are 

 very dark purple-brown, closely and regularly spinulose all over, 

 1-4 /x diam. (PL 386, fig. 5). On Nov. 16th, 1897, 1 had another fine 

 gathering from Miss Agues Fry, from Failand, near Bristol ; it was 

 part of an abundant growth on an old heap of stable manure in an 

 open field. This specimen differs from that sent by Mr. Crouch in the 

 larger size of the sporangia, which are irregularly ellipsoid, and all 

 sessile on a profuse white hypothallus. The capillitium and spores 

 are similar to the last and quite typical. The inner sporangium- 



