Reports and Proceedings — Geological Societij. 91 



The phenomena of metamorphism are then discussed, but no 

 additional facts of any great importance are brought to light. The 

 author expresses the opinion that the various gneisses of the district 

 in question were originally clastic rocks, somewhat perhaps of the 

 nature of a quartz-felspar grit ; and that the saussurite-gabbro, 

 diorite, diorite-schists, hornblende-schists, and related rocks were on 

 the other hand originally eruptive rocks or their tuffs. 



Some interesting facts with regard to gneiss and gneiss-granite are 

 then referred to, and the author concludes by expressing the opinion 

 that certain granitic areas may be regarded as portions of the funda- 

 mental series which have been pushed through later rocks by the 

 enormous earth pressure whilst in a plastic condition. 



I^sI=o:E^TS jlistid ^^s-oozEEnDiisrca-s. 



Geological Society oe Lonbok. 



L— December 19, 1883.— J. W. Hulke, Esq., F.Pt.S., President, in 

 the Chair. — The following communications were read : — 



1. "On some Eemains of Fossil Fishes from the Yoredale Series 

 at Leyburn in Wensleydale." By James W. Davis, Esq., F.G.S. 



After describing the nature and succession of beds among the 

 rocks which yielded the fossils under consideration, the author dis- 

 cussed the conditions under which they were deposited. He pointed 

 out that the Fish-fauna of the Yoredale series was distinguished by 

 some important peculiarities from that of the Mountain Limestone 

 below, as also from that of the Coal-measures. Some of the Car- 

 boniferous-Limestone types are represented only by very small 

 specimens in the Yoredale series ; certain Coal-measure fish make 

 their first appearance in these Yoredale beds; but a large propor- 

 tion of the species in the latter are peculiar to the formation. 



Of the thirty-four species cited twenty are identified with known 

 Carboniferous-Limestone forms, namely : — Cladacanthus paradoxus, 

 Ag. ; FJiysonemus Jiamatus, Ag. ; Cladodus mucronatus and Eornei, 

 Davis, and C. striatus, Ag. ; Pristicladodus dentatus, McC, and con- 

 cinmis, Davis ; Glyphanodiis tenuis, Davis ; Petalodopsis tripariitus, 

 Davis ; Polyrhizodus Colei, Davis ; Piclitodus scitultis, Davis ; Peta- 

 lodus acuminatiis, Ag. ; Pleurodus Woodi, Davis ; Poecilodus corru- 

 gatits, Davis ; Lophodus reticulatus, serratus, and hifurcatus, Davis ; 

 Psammodus rugosiis, Ag. ; Copodus cornutus, Ag. ; and Ctenopetalus 

 crenatus, Davis. The Coal-measure species, Megalichthys Hihherti, 

 is also cited. The remaining thirteen species are described as new ; 

 they are: — Chomatodus lamelliformis, Sandalodus minor, Lopliodus 

 conicus and angularis, Deltoptychius pUcatiis, and the following, 

 which are regarded as the types of new genera ; Gompliacanthus 

 acutus, Hemicladodus unicuspidatus, Astrahodus expansiis, Cyrto- 

 nodus giJibus. Echhiodus paradoxus, Diplacodtts biUboides, Mycetodiis 

 verrucosus, and Gercidognathus canaliculatus. 



In conclusion, the author noticed the occurrence, associated with 



