Geological Society of London. 281 



produced the great Condrusian ridge, producing anticlines and 

 synclines having a general east-atid-west trend, can be made out. 

 The rocks forming the subject of the present paper occur in one 

 limb of a complex anticline produced during the latter set of move- 

 ments. In this limb beds of the following ages occur : Tremadoc 

 Slates, Lower and Upper Arenig, Llanvirn, Llandeilo, and Bala. 

 These beds are described in detail. A regular succession of strata 

 from Tremadoc Slates to Dicranograptus-shales is found, while the 

 Bala beds of Mount Pleasant abut on Arenig strata, and the reason 

 for this irregularity has not yet been decided by the authors. The 

 beds are compared with those of other areas. The Tremadoc Slates 

 are equivalents of Stage 3a of the Christiania district ; the Lower 

 Arenig Beds with Phyllograptus angustifolius, and the Upper Arenig 

 with Didymograptus nitidus, etc., resemble those of other British 

 areas ; the Llanvirn Beds contain Didymograptus bifidus and other 

 fossils ; the Didymograptus Murchisoni-heds are well known else- 

 where. The Llandeilo Limestone is probably presented by sandy 

 beds with Asaphus tyr annus ; and the Dicranograptus-shaAea are like 

 those of the Haverfordwest region. The Bala Beds of Mount 

 Pleasant contain Stygina Murchisona and other fossils found 

 elsewhere in Bala rocks. 



A description of new fossils forms the concluding portion of the 

 paper. 



II.— April 29th, 1896.— Dr. Henry Hicks, F.E.S., President, in 



the Chair. 

 The following communications were read : — 



1. " Descriptions of New Fossils from the Carboniferous Lime- 

 stone. — (1) On Pemmatites constipatus, sp. nov., a Lithistid Sponge. 

 (2) On Palceacis humilis, sp. nov., a new Perforate Coral ; with 

 Remarks on the Genus. (3) On the Jaw-apparatus of an Annelid, 

 Eunicites Beidii, sp. nov." By George Jennings Hinde, Ph.D., 

 F.G.S. 



(1) The Pemmatites, belonging to a genus hitherto only known 

 from the Permo-Carboniferous beds of Spitzbergen, was discovered 

 in the Yoredale Beds of Yorkshire by Mr. J. Rhodes, and is the 

 only fairly complete sponge which has hitherto been detected in the 

 Yoredale Beds of North-west Yorkshire. The author gives a full 

 description of the species. 



(2) The Palceacis was found by the Rev. G. C. H. Pollen in the 

 Carboniferous Limestone and Shale Series, on the banks of the 

 Hodder, near Stonyhurst. The specific characters of the form are 

 given by the author, who then remarks upon the genus Palceacis, 

 which has been placed alternately with the corals and sponges, 

 though latterly it has been generally regarded as a perforate coral. 

 Nevertheless, its real characters had not been definitely settled : the 

 uncertainty, in the author's opinion, being due to the fact that some 

 writers have placed in the genus certain forms which differ widely 

 from the typical species, and have then defined the characters of the 



