223 



FOSSILS OE THE AEEAN EOCKS. 



105. THE following is a list of all the fossils yet disco vered 

 in the various sedimentary formations of Arran, corrected up 

 to the present time. Many of the best fossils in the list are 

 from the collections of Mr. John Young, Hunterian Museum, 

 Glasgow University, and Mr. James Thomson, an active 

 member of the Glasgow Geological Society. Mr. Nelson 

 Mitchell and Mr. Thomas Chapman have kindly supplied 

 several good species. The Corriegills' Orthoceras could not 

 be specifically determined, on account of the change produced 

 by a trap dike on the sandstone in which it was imbedded. 

 The list of Arctic shells was kindly supplied by the Rev. 

 Robt. Boog Watson of Edinburgh, their first discoverer, who 

 also, in the most prompt and kind way, placed at my dis- 

 posal all the information in his power in regard to the 

 localities whence the shells were obtained. The Rev. H. W. 

 Crosskey selected for me the Foraminifera found in the shell 

 bed, and forwarded them to Prof. Rupert Jones, to whose 

 kindness I am indebted for the names of the species. 



THE SLATES. 



No trace of any fossils.* 



THE OLD RED SANDSTONE. 



Markings on the South Sannox beds look like fucoid or 



* Yet, if the views of Sir K Murchison in regard to the structure 

 of the central Highlands be correct, these slates must be regarded 

 as of Silurian age. Metamorphic action may have obliterated all 

 trace of fossils. 



