Geological Society of London. 381 



After reviewing the discovery of Palceaspis and noticing cases 

 where Scaphaspid plates had been referred to ventral plates of 

 Pteraspidian fish, the author describes two specimens of his genus 

 Palceaspis from the Onondaga group (referred to the Lower Ludlow) 

 which indicate the existence of a ventral plate in this genus. The 

 evidence in favour of this interpretation is given at length, and the 

 fossil originally described as P. hitruncata is maintained to be the 

 Scaphaspid plate of P. americana. 



The existence of lateral plates and of lateral organs (' fins ') is 

 also discussed, and a comparison made between Palceaspis and other 

 Pteraspids. The author attempts a restoration of Palceaspis, and 

 gives an amended definition of the genus. 



6. " Contributions to the G-eology of the Wengen and St. Cassian 

 Strata in Southern Tyrol." By Maria M. Ogilvie, B.Sc. (Commu- 

 nicated by Prof. C. Lapworth, LL.D., F.R.S., F.G.S.) 



In the first part of this paper the authoress gives a summary of 

 previous investigations and speculations respecting the sequence and 

 fossils of the Triassic rocks of the well-known Dolomitic region of 

 Southern Tyrol ; more especially with reference to the famous fossil- 

 beai'ing strata of the neighbourhood of St. Cassian. The different 

 views which have been advanced with regard to the actual mode of 

 formation of these strata, and their proper classification, since the 

 appearance of the classical works of Von Eichthofen and Mojsisovics, 

 are indicated, and their geological significance discussed. 



In the main body of the paper the authoress gives a generalized 

 account of the results of her own personal study of these strata 

 during the years 1891-1892, illustrating her conclusions by maps and 

 sections. Three areas have been partly mapped in detail, on the 

 scale of 1 : 25000, and the various fossiliferous zones have been 

 traced on the gi'ound. The range and nature of the faults, etc., 

 have in this way been determined. 



The typical area of Prelongei and St. Cassian is first described in 

 detail, and from a careful mapping of the ground and a study of 

 the fossils the authoress reaches the conclusion that the St. Cassian 

 strata are naturally separable into three divisions, viz : — 



1. Upper Cassian Beds (or Prelongei Zone). 



2. Middle Cassian (or Muren Zone). 



3. Lower Cassian (or Stoures Zone). 



Each division is characterized by certain special lithological 

 features and paleeontological characters, everywhere recognizable. 

 In opposition to the views of some other investigators, it is shown, 

 by physical and palseontological evidence that the Upper Cassian 

 series is normally succeeded, as originally asserted by Von Eichthofen, 

 by the well-known Schlern Dolomite, and that between this band 

 and the massive Dachstein-Kalk there is invariably found the peculiar 

 zone of the Eaibl strata. 



The physical and pala^ontological relationships of the disputed 

 strata of the Eichthofen Eiff and Sett Sass are next discussed. The 

 richly fossiliferous strata of Heiligenkreuz are shown to include 



