56 
[PHYSARUM. 
membranous with innate clusters of white lime-granules. Colu- 
mella none, or represented by confluent lime-kuots. Oapillitium 
of branching hyaline threads, with numerous white lime-knots 
varying in size and shape, sometimes confluent in the centre of 
the sporangium or forming a Badhamia-hke network with few 
hyaline threads. Spores bright violet-brown, almost smooth or 
spinulose, 7 to 10 diam. — Kost., Mon., p. 102, figs. 71, 72, 85 ; 
Cooke, Myx. Brit., p. 13 ; Mass., Mon., p. 298 ; Macbride, in Bull. 
Nat. Hist. Iowa, ii., p. 155, PI. ix., fig. 4. Lycojjerdon cinereum 
Batsch, Elench. Fung., p. 155 (1783). Diclymium so-ohiculatuvi 
Berk., in Hook. Journ. Bot. (1845), p. 66. Physaruvi scrobicu- 
latum Mass., Mon., p. 300. 
Plate XVIII., A. — a. sporangia, x 20 ; &. capillitium and spores, x 280 ; 
c. spore, X 600 (England). 
Plate XYIII., B. — a. sporangia, x 20 ; i. capillitium attached to colu- 
mella and spores, x 280 ; c. spore, x 600 (Germany, Rostafinski's type of 
Crateriacliea imitahilis). 
The capillitium of P. cinereum varies widely in the development of 
the lime-knots ; in the common forms they are very numerous and 
rounded. Sometimes they are large and angled, and at other times 
small with the hyaline threads profuse. They are usually equally dis- 
tributed among the capilhtium, but occasionally more concentrated in 
the middle of the sporangium. A remarkable instance of the latter 
state is seen in the form named by Rostafinski Crateriachea mutabilis 
(Mon., p. 126), the type of which is in the Strassburg collection. 
Here the lime-knots are confluent, forming a distinct columella, a few 
also appearing among the network of hyaline threads by which it is 
surrounded. The sporangia are mostly elongated plasmodiocarps with 
scanty, brownish-yellow hypothallus, but some are ovoid or subcylind- 
rical, erect on a short brown stalk, the brown colour extending into the 
lower part of the sporangium-wall. The specimen issued by Raben- 
horst and Winter from Pavia No. 2969 (B. M. 542), wrongly named 
Didymium squamulosum, resembles Crateriachea in the sporangia being 
occasionally provided with a short brown stalk, and in the lime-knots 
being confluent and forming a pseudo-columella, but they are less 
densely compacted and more distributed among the surrounding capilli- 
tium ; the sporangia are also nearly globose. In the form named by 
Cesati Didymium Neapolitanum (B. M. 573),* the lime-knots are con- 
fluent, forming a large central mass more or less attached to the base 
of the sporangium ; the surrounding capillitium either consists almost 
exclusively of hyaline threads, or has a few large scattered lime-knots 
in addition ; the sporangia are irregularly globose, sessile, or on a buff 
foot-like hypothallus ; the spores in these three specirnens are the same 
as in P. cinereum. How far Crateriachea mutabilis, Didymium Neapoli- 
tanum, and the Pavia specimen above mentioned may be held to be 
varieties of P. cinereum, or as distinct species, must depend on further 
gatherings establishing the constancy of their forms ; as the occasional 
aggregation of lime-knots is of frequent occurrence in other species of 
Physarum, and in the somewhat nearly allied Badhamia panicea, this 
character can scarcely be considered important. It appears from 
* Two species were issued by Rabenhorst and Winter under the name 
Didymium Neapnlitaimm Ces., No. 2675 ; that in the Kcw coll. (657) is 
B. sqnamulomm, that in the Britisli Museum (573) is the species above 
described. 
