It has generally been held that the family Encrinuridae contains the four genera Encrinurus, Cybele, Cromus, and Dindymene, though Cromus is sometimes regarded as only a sub-genus of Encrinurus. The distinctive features of Encrinurus and Cybele as usually understood have been described and discussed by many authors, especially Salter, Nieszkowski, and Schmidt, but in 1877, Woodward considered Cybele to be only a sub-genus of Encrinurus. Dindymene is sufficiently distinct from the others to have had generic rank always accorded to it.

In the first part of this paper an account has been given of the heavy minerals of the northern part of the Leinster Granite and of the contiguous rocks in the Ballycorus district.

In the Geological Magazine for 1895 and again in 1898 W. M. Hutchings gave a petrological description of a shale, metamorphosed by the Whin Sill of Teesdale, which showed three unusual features. Scattered irregularly through the hardened shale were large nodules about the size of a pea which Hutchings considered to be the results of the metamorphism, in fact to be unusually well-developed “spots”. The second peculiarity was that both matrix and nodules contained considerable amounts of an isotropic material which was maintained to be the result of incomplete crystallization of a dense solution formed from the constituents of the shale during metamorphism. Finally, the detrital quartz grains of the shale were found to be extensively replaced by muscovite or more rarely other minerals. A reexamination has been made of the rock and also, by the courtesy of Professor G. Hickling, of Armstrong College, Newcastle-upon-Tyne, of certain of Hutchings's slices. In this note it is not intended to redescribe what has been ably described in Hutchings's papers, but as briefly as possible to make two corrections of Hutchings's conclusions.