286 Reports and Proceedings—Geological Society of London. 
last-mentioned mutation becomes predominant, and persists up to the 
Millstone Grit, where the septa become more amplexoid. 
All these mutations, in neanic life, have characters seen in adults 
of the preceding form; tachygenesis is so marked that earlier 
ancestral traits are rarely seen. 
Mutational percentages are given for many localities in the 
Carboniferous Limestone Series of the Central Valley, together 
with an analysis of the data so obtained. 
Brief diagnoses of the four new species are appended to the paper, 
Eee with full locality-lists. 
2. ‘The Carboniferous Limestone South of the Craven Fault 
(Grassington—Hellifield District).”” By Albert Wilmore, B.Sc., F.G.S. 
As to the lithology of the beds, some are massive, coarsely stratified 
limestones, made up largely of crinoids, or corals, or shells (or 
mixtures of these); others are well-bedded, almost flaggy, black | 
limestones made up of finely comminuted matter, with abundant 
Foraminifera. There is every gradation between these extreme types. 
Variation in lithological character is lateral as well as vertical. 
The strata are much disturbed everywhere. A series of folds 
strike roughly north-east and south-west, and are somewhat complex. 
There is considerable repetition of beds, and thickness is not so great 
as at first appears. This bears on the interesting question of the 
comparison of beds north and south of the Craven Fault. 
The well-known knolls (‘reef-knolls’) are discussed. Their beds 
and those in the immediate neighbourhood are much disturbed, 
Irregular coarse bedding, folding, and normal long - continued 
weathering will explain most of their structural and other peculiarities. 
A typical knoll is dissected (Swinden); and it is seen to consist of 
folded, faulted, grey, coarsely-bedded limestone, with numerous great 
joints ‘and much evidence of internal ‘ weathering’. Comparison of 
these knolls is drawn with the corresponding hills in the dark well- 
bedded limestones. 
It is not easy to work out the exact zonal sequence, because of the 
disturbed character of the strata and the prevalence of glacial and 
fluvio-glacial drifts. The strata are apparently all Viséan (and the 
author does not think that there is anything lower than Middle or 
Upper 8). 
In some beds, and under some circumstances, fossils are exceedingly 
plentiful and easily procured. 
Some corals receive more especial notice, such as Caninia gigantea, 
Mich., which is distinctive of certain beds. Other species of Caninia 
are found. New or not well-known species of Zaphrentis are described. 
The author briefly discusses the relationships of the genera Caninia, 
Campophyllum, Calophyllum, Zaphrentis, and Amplecus. New (?) 
species of Lophophyllum are also described, and the generic characters 
of Lophophyllum are discussed. There is a remarkably localized 
distribution of some corals, and Syringopora is very common in certain 
of the beds. 
Suggestions are made as to the advisability of the disuse of some of 
the specific names. It is suggested that not more than four species 
of Carboniferous Syringopora need be retained. 
