Ecology and Phenology of Surrey Mycetozoa. 6i 



var. rohiistum is frequent and has been found on laurel in 

 May and on elm in November and throughout the ^^inte^ and 

 spring. It is neariy always on rotting wood. 



*I2. P. crateriforme Fetch. After an exceptionally wet period 

 this species was found for the first time in England, gro\^ing 

 among hchens and associated with Crihraria aurantiaca, on an 

 old pine stmnp on St George's Hills, in September 1921. The 

 sporangia were so minute, and blended so well with the white 

 tops of lichen, that the}- could not be distinguished with the 

 naked eye, and it was only the appearance of some strange 

 looking spores among those of the Crihraria that provoked a 

 further examination of its well-concealed lurking place. 



jiS- P. pusilliim Lister. A minute slender form of this species 

 is frequently met with in heaps of old straw. In August and 

 September a sturdy, robust form appeared in great profusion, 

 on old pieces of white poplar bark, and in October it was again 

 met with on the leaves of Agave americana. 



♦14. P. compressum Alb. and Schw. can be found at almost 

 any time of the year. In February it occurred on the straw- 

 thatch of a haystack, in July a less robust form was running 

 wild over dead ivy leaves, in September a stout growth appeared 

 on willow bark and hme logs. A black stalk instead of a white 

 one is sometimes met with, while sessile sporangia of a hght 

 brown colour are not unfrequent, and hmeless sporangia have 

 been noticed in December. 



♦15. P. straminipes Lister, has only once been encountered, 

 although it is probably not uncommon in heaps of rotting straw. 

 One good gathering of this species was made during a ver\- wet 

 Julv at Horsley, on the edge of a straw heap just where it 

 mingled with the surrounding grass. It is hke P. didennoides in 

 the field, but its identity is instantly revealed under the micro- 

 scope by the unmistakable patches of warts on the spore. 



*i6. P. didermoides Rost. This is much more frequent than 

 the last named species and occurs in similar situations from 

 June to early autumn. It has also been foimd in August on 

 horse manure on a flower bed. 



17. P. cinereiim Pers. though especially a spring species may 

 be found at other seasons also; but from ^larch onward it has 

 occurred plentifully on dead leaves of oak, beech, sweet chestnut, 

 svcamore. hoUy, pine, poplar and bramble. Limeless sporangia 

 almost black and iridescent are frequently met with in con- 

 junction with the t^-pical form. 



18. P. verninn Somm. has been gathered in Januar}^ March 

 and April on old leaf beds. In the spring of this year (1923) 

 there appeared a form looking ver\' like Didcrma spiimarioides 

 extemall}-; it was densch' charged with hme and much nearer 



