XVII.—The Actinopterygian Fishes from the Lower Carboniferous of Glencartholm, Eskdale, Dumfriesshire

Abstract

Nearly sixty years ago fossil fishes were first discovered at Glencartholm, since when so much material has been collected from this locality that very few museums in the British Isles are without some representative of this remarkable fauna; remarkable both for the number of specimens collected and for the variety of forms it contains. One of us (J. A. M.-T.) became interested in this fauna while studying some of its more problematical members, and spent a few weeks collecting at Glencartholm during the summers of 1933, 1934, 1935 and 1936. During these visits a large quantity of new material was amassed which, when studied by modern methods with a low-powered binocular microscope under liquids, particularly xylol, revealed far more of the anatomy than it had been possible for earlier workers to describe. Some of these results have already been published and the present paper deals only with the Actinopterygians. The new descriptions in this work are not intended to be exhaustive accounts of all that is known of these fishes, but merely to serve as a supplement and summary to the excellent descriptions of Traquair. In so doing an attempt has been made to re-define all the genera and species, and in some cases it has been necessary to repeat the existing description, but where this has been done care has been taken to be as brief as possible. The definitions of the genera are only intended to apply to the species here described, and are consequently confined to characters which are determinable in these species. In certain cases species have been found to exist on brief and inadequate descriptions, in two species the type specimens being unfigured; in these cases the types have been figured, and new and more complete accounts given. Where the shape or ornament of a bone was indeterminable, it has been omitted without comment, in order to make the text as short as possible.