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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



the " zone of Ammonites Jason " of Dr. Wright. Except in the 

 somewhat more sandy character of the beds, this part of the Jurassic 

 series in Sutherland is scarcely distinguishable, either in petro- 

 logical or palseontological characters, from its equivalents in many 

 parts of Suabia, France, and England. 



The principal fossils of these beds, so far as they are known to 

 me, are enumerated in the following list : — 



Fossils of the Argillaceous series above the Brora Coal-series, 

 (Ornatus-cZays, Zone of Ammonites Jason, Wright). 



Belemnites Owenii, Pratt, var. Puzo- 

 sianus, I)' Orb. 



hastatus, JDe Bkdnv. 



Ammonites ornatus, Schloth. 



Jason, Reinecke. 



Gulielmii, Sow. 



Comptoni, Pratt. 



Duncani, Sow. 



Sedgvici, Pratt. 



Lonsdalei, Pratt. 



Elizabethan, Pratt. 



Bakerias, Sow. 



Koenigi, Sow. 



Eeginaldi (?), Mor. 



athleta, Phil. 



Chemnitzia heddingtonensis ?, Sow. 



Cerithium muricatum, Sow., sp. 

 Alaria bispinosa, Phil., sp. 



, sp. 



Myacites, sp. 



Thracia, sp. 



Cardium, spec. nov. 



Isocardia tenera, Sovj. 



Corbula oxfordensis, IS Orb. 



Nucula, sp. 



Lucina, sp. 



Cucullaea, sp. 



Avicula, sp. 



Pecten, sp. 



Grypbtea dilatata, Sow., var. 



Ostrea, sp. 



Wood (very abundant). 



The highest part of the argillaceous series passes up into the ma- 

 rine sandstone strata above by insensible gradations, the arenaceous 

 elements by degrees preponderating over the argillaceous in the 

 composition of the rock. These higher beds, forming the transi- 

 tion between the two series, are generally very unfossiliferous, and 

 yield only an occasional Belemnite (B. sulcatus, Mill., or B. Owenii, 

 Pratt) or cast of a bivalve. They consist of very sandy clays, with 

 nodular bands of argillaceous limestone, and are well exposed, to the 

 thickness of upwards of 70 feet, in the cutting above the Water-of- 

 Brora (Eascally) coal-pit. The argillaceous limestone here was at 

 one time burnt for lime ; and near the same spot the clays were dug 

 for brick-making. 



The series of beds just described appears to be brought up 

 again by the transverse fault already noticed to the south of 

 Strathsteven, and is '-exposed in a number of trial-holes in the 

 brickyard at Clayside,) where, however, very few species of fossils 

 have been obtained, these being almost entirely limited to some 

 fragmentary specimens of Belemnites sulcatus, Mill., and Belemnites 

 Oivenii, Pratt. The clay can also be traced, at several points be- 

 tween Clayside and Dunrobin, underlying the marine sandstones to 

 be afterwards more particularly noticed ; here, however, they are only 

 seen in a few road-side cuttings and in the burns. 



At Cadh'-an-Bigh, in Boss-shire, the roof-bed is covered by the 

 following series of beds (Fig. 8, p. 125) : — 



{a) Dark blue, very finely laminated shale, with some bands and flattened 



