HAUEK DACHSTEIN BIVALVE. 



cliaracteristic forms of the Upper Gault. All these forms occur ex- 

 clusively within the subdivisions 1 and 2, distinguished by the local 

 denominations of the *^ Nana beds" and the "Penzeskut beds"; 

 no Cephalopods having as yet been found in the subdivisions 3 to 6. 



[Count M.] 



On the Dachstein Bivalve. By Fk. von Haidee.* 

 [Proceed. Imp. Acad. Vienna, December 5, 1861.] 

 One of the most striking features of Alpine geology is the enor^ 

 mous development of limestones and dolomites, forming, in the north 

 and south, secondary zones and groups of mountains, in more than 

 one instance rivalling in height those of the Central Alpine range. 

 Stratigraphical and palaeontological investigation of the marly and 

 arenaceous strata (the Parttnach-, St. Cassian-, Eaibl-, and Koessen- 

 strata) have led to a subdivision of these limestone and dolomite 

 masses into Hallstatt- and Esino-strata, Great Dolomite, Dachstein- 

 timestone, &c. 



Wherever the marly or arenaceous intercalations are wanting, 

 the determination of the relative age of these massifs, generally but 

 scantily provided with determinable organic remains, becomes a 

 difficult task. The large bivalves alone, termed " Dachstein-bivalves " 

 on account of their frequent occurrence on the elevated plateau of 

 this mountain-group, are generally spread through the massifs in 

 question. These bivalves, which have had successively many dif- 

 ferent systematic names, are stUl in want of a more accurate specific 

 determination, and of a satisfactory statement of their geological 

 and geographical distribution. This is a task the more difficult as 

 complete specimens, fit for the preparation of the hinge and other 

 characteristic parts, are not easily obtained out of the solid rock. 



Pive distinct species of the genus Megalodus have hitherto been 

 more or less confounded under the current denomination of " Dach- 

 stein-bivalve." Among them Megalodus triqueter (the most fre- 

 quent) and M. gryplioides are peculiar to the Dachstein-limestone 

 and the Koessen- strata ; M, complanatus is characteristic of the 

 Great Dolomite ; M. lamellosus of the Raibl-strata ; and M. Colum- 

 hella of the Halls-tatt-beds. [Count M.] 



On some Fossil Betozoa. By Dr. Stoliczka. 

 [Proceed. Imp. Acad. Vienna, December 12, 1861.] 

 The Oligocene fauna of Latdorf (in the Duchy of Anhalt-Bernburg) 

 numbers a total of 158 species : among these are 47 species of Bryo- 

 zoa, in 18 genera. Two of these genera (Orhitulijpora and StichO" 

 porina) are new ; above half (24) of the species are undescribed. 



The distribution of Bryozoa in the Tertiary deposit of the VieniiaL 

 basin offers the following facts : (1) with increasing depths the 



* In a Eeport on a Memoir by M. H. Giimbel. 



c2 



