On the Occurrence of Species of the Genus Diphyphyllum , Lonsdale, in the Lower Carboniferous Strata of Scotland, with a Description of some new Species and Notices of Varieties

Abstract

The object of this communication is to offer evidence in favour of the recognition of the genus Diphyphyllum , which was defined many years since by Lonsdale, and which has not been definitely accepted by any palæontologist, with the exception of M'Coy. It is proposed to give a slight history of the genus and species, and then to notify the occurrence of all the species with varieties in somewhat remarkable deposits in the Lower Carboniferous series of Scotland, and to describe two new species and a variety of one of them. The facts now brought forward clearly prove the truth of Lonsdale's diagnosis of the genus, which enters the family Cyathophyllidæ of the Rugosa, and also necessitate the introduction into the generic diagnosis of the words “increase by gemmation and by fissiparity.” The genus Diphyphyllum was defined by Lonsdale in Murchison, Keyserling, and De Verneuil's 'Geology of Russia and the Urals'(appendix, p. 622), and the type of the species D. concinnum , Lonsd., is in the collection of the Geological Society of London. The definition was as follows :—“ A stony lamelliferous polypidom ; lamcllm exceeding 12, biplated ; branched, branches dichotomous ; internal structure, triareal—1, central area intersected by flat, convex, or irregular diaphragms, no persistent axis ; 2, intermediate arca traversed vertically by lamellæ, interspaces crossed obliquely or downwards by extensions of the diaphragms and subordinate plates; 3, outer area traversed by lateral extensions of lamellæ, interspaces crossed by arched or vesicular laminæ inclined upwards and outwards ; stems not