GEOLOGY. 



39 



Lord Kinnmnl and the Rev. Dr. Joliu Anderson, wliose able 

 work on that beautiful tract is well known to geologists, and 

 now I entertain no doubt whatever, that the yellow sandstones 

 with red layers pertain truly to the Old Red group, that they 

 are entirely subjacent to the equally yellow carboniferous sand- 

 stones with coal plants, and are of about the same age as the 

 yellow sandstones of Elgin. A splendid specimen of the genus 

 holoptychius, three feet long, was found on the occasion of this 

 visit, on the property of Mrs. Dalgleish ; and as a form very 

 similar abounds also in the lower red portions of the deposit at 

 Clashbennie, the age of the yellow sandstone is clearly substan- 

 tiated. . . . Dr. Anderson is now convinced that this splendid 

 specimen, now in the collection at Rossie Priory, is truly the 

 Holoptychius Andersoni of Agassiz. 



" He further informs me that the yellow sandstones of Dura 

 Den contain ichthyolites of the genera Platygnathus, Diplo- 

 pterus, Glyptopomus, Holoptychius, Pterichthys (Pamphractus), 

 with a new genus, an assemblage which shows that certain 

 genera range from the Caithness flags, or central portion of 

 the Old Red group, up into its highest zone. Dr. Anderson's 

 finest specimens are in the British Museum.""'' 



Homocercal. 



* Silarla, Tliiril Edition, pp. 553, 556, 559, 57-1. 



