820 DR J. W. GREGORY ON 



decidedly plant-like growth. The stems are flattened, and the fossil appears to be 

 one of those plant-like impressions which are conveniently regarded as fncoids. 



A photograph of one of these fncoids is reproduced as Plate XCII, fig. 8, and this 

 fossil closely resembles Buthotrephis succulens, Hall, from the Trenton Limestone of 

 Glen Falls in the State of New York. Its stem, where 5 mm. across, is 1^ mm. thick, 

 so that it agrees with Buthotrephis rather than with Palseophycus, in which the 

 stems are more cylindrical. I only know Buthotrephis succulens from Hall's # 

 original figure and description, and the South Georgian specimens are very similar to 

 it. The resemblance may be purely accidental. It is, however, interesting to note 

 that the Camarocladia bed in Illinois is described by Ulrich and Everett t as 

 crowded with Buthotrephis and Palseophycus. 



During a study of the microscopic structure of these rocks Mr Tyrrell found a 

 series of radiolaria in various specimens, and they are especially well preserved in 

 one band belonging to the middle division of the Cumberland Bay Series at Cape 

 Pariadin. Some sections have been kindly examined by Dr Hinde. He reports : 

 ' The following genera appear to be represented : — Cenos'phtera, Cenellipsis, Amphi- 

 brachium, Archicapsa, Dicolocapsa, Tricolocapsa, Dictyomitra, and Stichocapsa. 

 The three first-mentioned genera would be included in Haeckel's Spumellaria, the 

 other five in his Legion Nassellaria. At present I should consider from the general 

 character of the forms in these two sections that they are post-Pal?eozoic and pre- 

 Tertiary in age, and they might come in between the Triassic and the Cretaceous. 

 But this view might be modified by further knowledge from the contents of fresh 

 sections." 



Illustrations of the chief forms from drawings by Dr Hinde are shown on 

 Plate XCIII. 



Hence the Middle Cumberland Bay Series includes a band of rocks which accord- 

 ing to the cephalopod discovered by Dr Konig is probably Cretaceous, and according 

 to the radiolaria the age is probably Jurassic. According to Mr Ferguson's fossils 

 the lower division is probably Ordovician or Silurian. 



The conflicting paheontological evidence would be most easily explained by the 

 hypothesis that the lower division of the Cumberland Bay Series is Ordovician or 

 Silurian, and that the middle and upper divisions, which yielded the cephalopod 

 and the radiolaria, are Mesozoic. That part of this series is Palaeozoic is supported 

 by the opinion of both Mr Ferguson and Dr Pirie that these rocks present a striking 

 lithological resemblance to the graptolite-bearing rocks of the South Orkneys. 



The lower beds are certainly ancient in aspect. Mr Tyrrell in his description 

 of the rocks refers to their resemblance to some of the beds in the Silurian, and 

 Ordovician rocks of the Southern Uplands of Scotland. Further, it is natural to 

 correlate the radiolarian jasperoids with those of Joinville Island off Graham Land ; 

 and Sir Archibald Geikie remarked in his description of them that the occurrence 



* Jas. Hall, PalseonL, New York, vol. i, 1847, p. 02, pi. xxii, fig. 2a. t Op. cit., p. 255. 



