530 Geological Society : — 



Southern Livonia. With but partial exceptions the Silurian series 

 of Esthonia is almost entirely composed of calcareous bands. 



The " Pleta," or the oldest and most northern group of the se- 

 ries, caps the cliffs of the Gulf of Bothnia, which are known as the 

 " Glint," and is based on the Ungulite grit and associated argilla- 

 ceous and sandy beds of the government of St. Petersburg. It is 

 of the age of the Lhmdeilo rocks, and is succeeded by coralline lime- 

 stones of the Caradoc or Bala age. The next series of strata com- 

 prise two bandsof Pentanieri (P. borealis and P. oblongus), representing 

 the Llandovery series. The succeeding group is developed partly 

 on the continent and partly on the north-eastern portion of the Isle 

 of Oesel, and chiefly consists of dolomites of the Wenlock age. In 

 the south-western portion of the island are still higher strata of the 

 Ludlow series, in which fish-remains are not unfrequent. 



In comparing these Scandinavian, Estlionian, and British Silurian 

 rocks together, Sir Roderick particularly dwelt upon — 1 . the natural 

 indivisibility of the alum-schists and Lingula-flags from the rest of 

 the Lower Silurian series; 2. the extensive occurrence of the Pen- 

 tamerus-zone, marking the passage-beds between the Upper and 

 Lower members of the series; 3. the general uniformity in the 

 distribution of the organic remains of the several successional groups 

 of beds, although the strata themselves are very variously developed, 

 as to mineral character and thickness ; and 4. the characteristic 

 agreement in fossils between the several Silurian areas of Northern 

 Europe, North America, Canada, and the Arctic regions, on the one 

 hand; whilst, on the other, the Silurian rocks of France, Spain, 

 Bohemia, the Ural, and probably of South America, are dissimilar 

 as a group, from their northern representatives, both in palseonto- 

 logical and lithological characters, marking the existence of distinct 

 geographical limits of life during the older palaeozoic period. 



In conclusion, the author stated that all the evidence tended to 

 prove that in Scandinavia, as in Russia in Europe, the Silurian rocks, 

 both Lower and Upper, form a united and unbroken whole ; and 

 that, both by fossils and by strata, they exhibit in those countries, 

 and in a very small compass, a natural-history system quite as com- 

 plete and more easily understood than their much more expanded, 

 highly varied, and dislocated equivalents in the British Isles. 



May 20, 1857.— Col. Portlock, R.E., President, in the Chair. 



The following communications were read : — 



1. " Description of a small Lojjhiodont Mammal {Pliolophus vul- 

 piceps, Owen) from the London clay, near Harwich." By Prof. 

 Owen, F.R.S , F.G.S. &c. 



The subject of tliis paper was a considerable portion of the ske- 

 leton of a small quadruped, about the size of a fox, imbedded in, and 

 apparently the nucleus of, one of the septarian nodules of the 

 London clay, which are dredged up at the mouth of the Thames 

 for the purpose of the manufacture of Roman cement. 



From this nodule were extricated the skull with the entire series 

 of teeth in both jaws, the right humerus, portions of the pelvis, 

 right femur, left femur, left tibia, and the three metatarsals of a 



