TEANSLATIONS AND NOTICES 



OF 



GEOLOGICAL MEMOIRS. 



The Fauna of the Lower Oltgocene Tertiary Beds of Helmstadt, 

 near Brunswick. By Herr V. Koenen. 



[Die Fauna der Unter-Oligocanen Tertiar schichten von Helmstadt bei Braun- 

 schweig. Von Herrn v. Koenen. Zeitschrift der Deutschen geologischen 

 Gesellschaft, Band xvii. pp. 459-534, 1865.] 



The author begins his Memoir with an historical notice of the dis- 

 coveries respecting these middle Tertiaries from the time of Miinster 

 and Goldfuss to the day when Beyrich introduced the term '' Oligo- 

 cene" between the Eocene and Miocene of Lyell, for beds, the 

 whole series of which only occur in J^orth Germany, where they are 

 purely marine, and therefore can in that region only he fully 

 studied and understood. He then proceeds to point out what he 

 considers a want of due appreciation of the Oligocene system on the 

 part of Sir Charles Lyell, who places the Headon and Bembridge 

 beds in the Eocene, and the Lower Oligocene, on the other hand, in 

 the Miocene system. He calls attention to his Memoir published in 

 the Quarterly Journal for 1864, p. 98, in which he has shown that 

 the Headon series is the exact equivalent of the Lower Oligocene, 

 inasmuch as out of bQ marine species, 6 are peculiar to the Headon 

 series, and of the remaining 50, 43 occur in the Lower Oligocene, 

 23 being peculiar to it, whilst only 21 species occur in the Upper 

 Eocene (Barton). He then shows that every one of the 152 species 

 from Edeghem, as quoted by j^yst, occurs in the Black Sand (Lower 

 Crag) of Antwerp (' Systeme Diestien ' of Dumont), and that con- 

 sequently it is incorrect to separate the Edeghem beds from the 

 Black Sand of Antwerp. 



Herr v. Koenen then points out the vast increase of material 

 which has been obtained for the better knowledge of the Oligocene 

 beds, since Prof. Beyrich first began his excellent work on the shells 

 of the North German Tertiary beds, but which he has so long left 

 incomplete. These fossils have been obtained chiefly from the 

 Middle Oligocene of Sollingen, and the Lower Oligocene in the neigh- 

 bourhood of Magdeburg. Other localities are also mentioned, most of 

 which had been already alluded to by the author in a Memoir published 

 in the ' Zeits. d. Deutsch. Geol. Ges.' 1863. p. 612, on the extent of 

 the fossiliferous beds of this formation. The green sands and yellow 

 clays of Helmstadt were then pronounced by the author to be Lower 

 Oligocene. Somewhat later Herr v. Strombeck, after a careful in- 

 vestigation of the beds in question, came to the same conclusion, 

 that they were Lower Oligocene. But in order to remove the possi- 

 bility of a doubt, Herr v. Koenen undertook the palaeontological 

 question by carefully working out the fauna of the Helmstadt beds. 

 Numerous collections, both from German localities, and from Belgium 

 and England, were placed at his disposal, and he particularly alludes 

 to Mr. Edwards as having afforded him the greatest assistance. 



The following section of the stratification at Helmstadt is taken 

 VOL. II. — part II. E 



