746 TRANSACTIONS OF SECTION K, 



seed-plants as well as the Ferns. The difficult question of the position of the 

 Ferns in the Palaeozoic flora is considered, the difficulty arising from the accumu- 

 lation of evidence showing that most of the so-called Palaeozoic Ferns were in 

 reality seed-plants. The conclusion is reached that a large body of true Ferns of 

 a simple type — the Primofilices of Mr. Arber — existed in Lower as well as Upper 

 Carboniferous times, the Botryopterideae constituting one special family of this 

 group . 



It is also considered probable that true Marattiaceous Ferns existed, though 

 many of the plants hitherto classed with them were certainly Pteridosperms. 



The position of the Pteridospermese as a distinct class of Spermophyta is con- 

 sidered, and the view is taken that, considering the very primitive characters 

 which they present, it is better to keep them separate from the Gymnosperms 

 a class which had departed so much further from Cryptogamic traditions. 



The evidence for the derivation of Pteridosperraeae from ancestors belonging to 

 the same stock with the Ferns is found to be of overwhelming strength. Their 

 origin, however, no doubt lay very far back, for Pteridosperms, and probably 

 even Cordaiteae, are among the oldest known land-plants. 



No great advance has been made of late in our knowledge of Palaeozoic 

 Gymnosperms. The Cordaiteae appear to belong to the same main phylum with 

 the Pteridospermese, while in another direction they show distinct affinity to the 

 Coniferae. 



In conclusion, attention is called to the very special nature of the floras from 

 which our knowledge of Palaeozoic plants is derived. Material from new sources 

 is urgently needed in order to extend our data. 



Recent research has been mainly carried on from a morphological point of 

 view. It is very desirable that the conditions under which Palaeozoic plants 

 grew, and the biological character of the vegetation, should also receive attention. 



2. On the Occu7'rence, Distribution, and Mode of Formation of the 

 Calcareous Nodules found in Coal Seams of the Lower Coal Measures. 

 By Professor F. E. Weiss. 



The petrified remains of Coal-measure plants, which through the investigations 

 of Biuney and Williamson, of Scott, Seward, and Oliver, have so largely increased 

 our knowledge of the past history of the vegetable kingdom, were chiefly contained 

 in calcareous concretions (the so-called ' bullions ') found in certain seams of the 

 Lancashire and Yorkshire coalfields. As first described by Binney, they were to 

 be found in three seams in Lancashire : in the 'Upper Foot ' or ' Bullion ' Mine, in the 

 Gannister coal, and in a very narrow seam of a lower horizon. Some confusion, 

 however, exists with regard to the two former seams owing to their union to form 

 the ' Mountain Four Feet,' seam, and there seems considerable doubt as to the occur- 

 rence of coal-balls in the Gannister coal. Indeed, it would seem now generally ac- 

 cepted that true coal nodules occur only in one single horizon (see Lomax, ' Annals 

 of Botany,' 1902). The nodules or bullions occurring in this Upper Foot seam (corre- 

 lated by Bolton with the ' Hard Bed ' seam of Halifax) vary from an inch to a foot 

 in diameter. They are concretions consisting mainly of carbonates of lime (45 to 

 70 per cent.) and of magnesia (10 to 20 per cent.), with small quantities of oxide and 

 sulphides of iron. Sometimes they are so numerous as to render the coal utterly 

 useless, and they may be found to occur over a space of several acres. They con- 

 tain a tangled mass of plant remains, often in a state of excellent preservation. 

 Shells are not found in these nodules, but are very common in similar nodules 

 found in the roof of the seam. According to Binney the occurrence of nodules in 

 the coal is always associated with that of fossil shells in the roof, and the nodules 

 may therefore probably be formed by calcareous salts in solution in water, which 

 became aggregated round certain centres in the submerged peaty mass of vegetable 

 matter. 



A similar mode of formation has been suggested for the calcareous nodules 

 (Dolomitkuollen), which occur in certain seams of the Westphalian coalfield, 



