BOTANICAL NOTES AND NEWS 253 



Preliminary to his investigation, Professor Penhallow classified his 

 material as follows : 



1. Rugose stems in which the organic matter has been wholly 



replaced by red oxide of iron. 



2. Rugose stems showing apparently leaves attached. 



3. Fragments of linear leaves (Cordaites augustifolia ?}. 



4. Linear leaves or branches. 



5. Oval impressions showing distinct reticulations "devoid of 



Parka discs, but showing a reticulated and somewhat 



radiating structure, evidently composed of' elongated 

 parenchymatous cells." 



6. " Discoid impressions of bodies represented by a somewhat 



carbonaceous residue, but showing no structure. Apparently 

 solid, spore-like spherules flattened by pressure." 



7. Fragments of Parka. 



Detailed descriptions of the various organisms are given ; but 

 the point of greatest interest centres in Parka decipiens, the examples 

 of which, owing to differences in point of size, are treated by Professor 

 Penhallow in three distinct groups. 



In group A they measure 6 to 1 1 mm. in diameter. 



In group B they measure about 13 x 20 mm. 



In group C, the most perfect specimen measured, 3-5 x 5-3 cm. 



Professor Penhallow believes that in these masses ''we must 

 recognise sporocarps containing globular sporangia (Parka discs)." 



The discs appear, according to this writer, to be invested by a 

 thick carbonaceous layer, which, when examined as an opaque object, 

 shows a reticulation of the surface. Internal to this the disc consisted 

 " of a distinct tissue, composed of rather thin walled cells, thus giving 

 direct proof that they were not simple spores, but of the nature of 

 sporangia. 



" In one or two cases they also appear to contain certain rounded 

 bodies similar to spines, at least distinct from the other parts of 

 the structure, but so involved as to leave their identity somewhat 

 in doubt." Certain isolated minute bodies were also observed, which 

 are regarded as microspores. He also figures and describes some 

 cellular structures which he believes to be prothalli. 



From the examination of the material at his disposal, 

 Professor Penhallow comes to the conclusion " that Parka is an 

 aquatic rhizocarp allied to Pilu/aria." 



He therefore defines the genus Parka as follows : 



Genus Parka, Flem. 



" Aquatic plants with creeping stems, linear leaves, and sessile 

 sporocarps having two kinds of sporangia. Sporangia, 2 mm. in 

 diameter; macrospores, 40 /z ; microspores, 15 //. 



