818 DR J. W. GREGORY ON 



records the presence in South Georgia of granitic and dioritic rocks, aplite, and a 

 centre of " altvulkanischer " basic eruptives, including diabase and melaphyre-like 

 rocks. Dr Heim remarks that the rocks are not sufficient to prove that the island 

 belongs to the folded mountain system of the Andes and Antarctic Andes ; but he 

 says that the folded Mesozoic beds, tuffs, basic eruptives, and associated plutonic 

 rocks of South Georgia and Graham Land form a striking geological reflection of the 

 Patagonian Cordillera. 



Mr Ferguson's work throws much fresh light on the geology of the island and 

 some doubt on the generally accepted view as to its relations. The fossils which he 

 collected in the slates and limestones of Stromness Bay are so crushed that their 

 identification is difficult. They include some vertical sections through what appear 

 to be massive cylindrical tabulate corals. The best specimen (Plate XCI1, fig. l) is 

 45 mm. wide and 70 mm. long ; its shape was obviously cylindrical or subcylindrical ; 

 it has thick walls ; there are no septa, but traces of septal structure occur in the wall ; 

 there is no internal vesicular tissue, but the specimen is crossed by 30 tabulae in 

 a length of 60 mm. This combination of characters is also met with in the coral 

 Omphyma. If the fossil be a coral it would belong to that or some allied genus. 

 Dr G. J. Hinde has kindly examined the specimen, and says that unless it be a coral, 

 it is very difficult to say what it can be. 



Mr Ferouson collected a series of csespitose organisms, of which one tuft 

 (Plate XCII, fig. 2) is 90 by 100 mm. in diameter; its branches subdivide dichotomously 

 and are, on an average, from 3 to 4 mm. in diameter. A thin section from this 

 specimen shows broken tubuli, which have some resemblance to those of monticuli- 

 poroids, and the fossil from which this section was cut has a habit similar to that of 

 some upper Ordovician and Silurian monticuliporoids. Dr R. S. Bassler has kindly 

 examined some of them, and reports that in the opinion of himself and his colleagues 

 in the National Museum, Washington, the fossils are either sponges or fucoids. 

 Dr Bassler remarks that " one of our Ordovician genera, Camarocladia, shows a 

 structure something like these specimens, and for a guess I would say that they are 

 nearest this genus. Mr Ulrich and I agree that they are not Bryozoa, because it is 

 our experience that no matter how great the crushing, specimens preserved as these 

 arc show some of the original structure." 



A second representative (Plate XCII, fig. 3) of this group of fossils consists of stems 

 as much as 6 mm. in diameter, and which are branchless for sometimes 75 mm. in 

 length. They appear to have a central axial space with transverse layers like the 

 tabulae of corals or the horizontal partitions of such sponges as I'vemacystia. One of 

 the specimens appeared to show a reticulate structure. I therefore sent it to Dr 

 (J. -I. IhxnK, w bo was, however, unable to recognise any definite evidence that it is a 

 sponge. The fossil may be a Camarocladia with long, unbranched stems, thougli it 

 might also be some alga with a partially segmented stem. 



The third type of these tufted fossils are smaller in diameter (Plate XCII, 



