LOWER CARBONIFEROUS ROCKS OF THE FIFESHIRE COAST. 403 
be the prevailing forms in a group of rocks, and any one accustomed to deal with 
such questions will hold the conclusion irresistible—that group is simply the 
Mountain Limestone. This is one of the best marked and most thoroughly under- 
stood portions in the whole series of ancient rocks. Powerfully developed in York- 
shire, it passes south by Bristol into Devonshire and Wales, crosses over into Ireland, 
where, north and south, the level of the great Scaur Limestone has been well 
recognised. Spreading over the kingdom, this belt of Mountain Limestone lies 
everywhere on the same geological horizon, and what we have here on the Fife- 
shire coast overlying the bed L is simply a powerful mass of strata forming a 
prolongation of the same great series. The limit of the group upwards I have 
not examined. 
The question, therefore, which suggested itself on the shore at Ardross, on 
_ first looking at the limestone bed with its fossils, has been satisfactorily solved. 
Its place is somewhere about 1400 feet above the base of that great series which 
is recognised over the kingdom as the Mountain Limestone proper. 
And now, in regard to the inferior group—the Lower Carboniferous—Mr Grrk1Ee 
recognising the insufficiency of the difference between the fresh-water and marine 
character of beds as a ground of distinction between the groups, has proposed to 
regard the whole carboniferous series beneath our coal-fields as the representative 
merely of the marine Mountain Limestone of Yorkshire.* There seems, however, 
reason to believe that the lower portion belongs to that antecedent period which 
ushered in the Mountain Limestone proper. Should this be confirmed, it will give 
_ special importance to our Scottish rocks, as casting valuable light on the obscure 
introductory stage of the carboniferous era. The difference of this group from 
the other is no doubt only one of degree, for both are carboniferous and belong 
to the same formation ; but referring back to the details of our general description 
in the preceding section, the following points may be noted as distinctive of the 
lower series, viz. :— 
1. The prevalence of Myalina beds throughout the strata below L. 
2. The comparative abundance of Sphenopteris affinis above L, and of Cyclop- 
teris below it. Both plants occur in both series, but their comparative abundance 
is markedly different. 
3. The most important point is that the carboniferous fauna of the Mountain 
Limestone is seen only in an incipient state. 
This was not for want of sea-room in which to show itself. There was room 
for Pectens, Modiolze, and Schizodi, just as in the limestones above and what is not 
less conclusive, there was room for Gasteropods like Murchisonia, Chemnitzia, 
Natica, and Cephalopods, like Orthoceras. But where are the Corals, the Encri- 
nites, the immense development of Brachiopods, all those great characteristic 
forms of life that make the Mountain Limestone fauna what it is. If they occur 
* See his interesting work ‘‘ The Story of a Boulder,” p. 195. 
