come mainly from the Upper Foot seam and more rarely from the Gannister coal (Stopes and %'atson, 1908, fig. 5). This is the richest coal-ball flora recorded as "Upper Foot" in our Tables 1 — 4. It may be noted that roof nodules containing an interesting, slightly distinct Aora have been col- lected more particularly from the roof of the Upper Foot coal at Shore and Oldham,

3. Recent studies on European coal balls
On coal balls from Lancashire

It is necessary to mention especially the recent and intensive collecting and research of John Holmes who, between 1972 and 1980, reinvesti- gated fifteen coal-ball localities, all from the Union scRIIl, Rlld collcctcd R 1R1'gc amount of material from coal tips at Rowley, Townley, Hapton Valley and Hill Top (Fig. 3). Prom 1975, after being informed of the Lancashire County Council pro- jects of landscaping the Burnley area, Holmes started R series of salvRgc opclatlons 011 threat- ened and rapidly disappearing coal tips. Holmes and I decided to improve the method of selecting coal balls. Each coal ball was sectioned and etched, Rnd ccllulosc RcctRtc pccls werc pl'cpR1"cd RIld examined under the microscope in the field. This allowed a more rigorous selection. As a result, from about two thousand coal balls, less than 400, containing diverse plant assemblages, were finally

Table 3

Occurrences of ferns in the different floras