94 Reports and Proceedings — Geological Society. 



Hitherto our knowledge of the Upper Jurassic Fish -fauna has 

 heen mainly derived from specimens found in line lithographic stones, 

 where the various elements are in a state of extreme compression. 

 Within the last few years remains of similar fish have been dis- 

 covered in the Oxford and Kimeridge Clays in England, and these 

 are of value for precise determination of certain skeletal features in 

 the genera to which they belong. 



The author described Eurycormus gravdis from the Kimeridge 

 Clay at Ely, a large species which makes known for the first time 

 the form and proportions of several of the head-bones in this genus. 

 A technical description of all the- bones the characters of which are 

 distinguishable was given, and the author concluded that there is 

 considerable similarity between the head of Eurycormus and the 

 recent Ganoid Amia, even to minute points of detail. 



He further described Hypsocormus tenuirostris and H. Leedsii 

 from the Oxford Clay of the neighbourhood of Peterboro', the oste- 

 ology of this genus not having as yet been elucidated. Poi'tions of 

 the jaws have been discovered, affoi-ding valuable information as to 

 the form and dentition of the principal elements. 



These jaws are not precisely paralleled by any other Jurassic 

 genus, though they possess a resemblance to Pachycormus, as also 

 to the Upper Cretaceous genus, Protosphyrcena. 



2. " On the Pebidian Volcanic Series of St. Davids." By Prof. 

 C. Lloyd Morgan, M.S. 



The Relation of Pebidian to Cambrian. — There are four localities 

 where the junction is described — Caerbwdy Valley, St. Non's Bay, 

 Ogof Golchfa, and Ramsey Sound. The stratigraphy of the second 

 of these was given with much detail, and illustrated. The author 

 concluded that here, together with clear signs of local or contem- 

 poraneous erosion, the general parallelism of the strike of Pebidian 

 and Cambrian is most marked. There is no evidence of any bending 

 round of the conglomerate against the strike of the Pebidians. The 

 stratigraphical evidence in each of the localities having been con- 

 sidered, together with the evidence offered by the materials of the 

 Cambrian conglomerate and local interstratification with the volcanic 

 beds (the interdigitation at Carnarwig being well marked), he con- 

 cluded that there was no great break between the conglomerate and 

 the underlying Pebidians. The uppermost Pebidian already fore- 

 shadowed the sedimentary conditions of the Harlech strata, and the 

 change emphasized by the conglomerate was one that followed 

 volcanic conditions after no great lapse of time. , 



Hence the relation of the Pebidian to the Cambrian is that of a 

 volcanic series, for the most part submarine, to succeeding sedi- 

 mentary strata — these strata being introduced by a conglomerate 

 formed in the main of foreign pebbles borne onward by a current 

 which swept the surface of, and eroded channels in the volcanic 

 tuffs and other deposits. He was disposed to retain the name 

 Pebidian as a volcanic series in the base of the Cambrian system. 



The Pebidian Succession. — With the exception of some cinder-beds, 

 which appear to be subaerial, the whole series was accumulated 



