176 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Jail. 8, 



Pecten subfibrosus, Sow. 



vimineus, Sow. 



, spec. nov. 



Placunopsis insequalis, Phil. } sp. 



, spec. nov. 



Gryphaea dilatata, Sow., var. 

 Ostrea Rcemeri, Quenst. 



Ostrea gregaria, Sow. 



Serpula intestinalis, Phil. 



— ,sp. 



Spine of Acrosalenia. 



Cliona (crypts). 



Ferns. 



Wood and Plant-remains. 



An examination of the faunas of the various limestones and clays 

 above the thick series of estuarine sandstones of the gorge of the 

 Brora shows that they all form part of the same marine series, 

 the beds of white sandstone only marking a partial interruption of 

 the marine conditions. The large series of fossils collected from 

 these marine strata fortunately leaves no room for doubt as to their 

 true geological horizon; the fauna is unmistakably that of the 

 Coralline Oolite of England. The correspondence of the fossils of 

 the Scotch beds with those of the English, in spite of the difference 

 of mineral characters, is very striking. 



Thus the Middle Oolite series of Sutherland is seen to be very 

 fully developed, attaining a thickness of at least from 800 to 

 900 feet, of which about one half is made up of marine strata, and 

 the other half of estuarine. 



South of Shandwick Bay, at Port-an-Bigh, on the coast of Boss- 

 shire, other beds of the age of the English Coralline Oolite, and 

 differing but slightly in mineral character from those of Suther- 

 land, are found. They consist of dark-blue shales, alternating with 

 and passing into beds of sandy argillaceous limestone. The clays 

 contain some septaria ; and towards the middle of the series there 

 are some beds of very hard and compact argillaceous limestone, 

 which weather to a red colour (figs. 6 & 7, pp. 124 & 125). 



Fossils are not generally very abundant in these beds ; but the 

 hard limestone bands are in places found to be crowded with Am- 

 monites. The most conspicuous fossil is the gigantic expanded 

 variety of Gryphcea dilatata, Sow. 



The thickness of beds exposed here is not very great, their strike 

 being generally parallel to the shore ; the breadth of their outcrop 

 probably does not exceed 100 yards, the dip being from 20° to 30°. 



The manner in which these beds are faulted against the Old Bed 

 Sandstone, and the curious way in which they are bent, contorted, 

 and broken up by small faults has been already described (see 

 p. 123). 



These beds have hitherto been usually classed with the Lias ; but 

 the following list of fossils contained in them proves conclusively 

 that their true horizon is that of the English Coralline Oolite. 



List of Fossils from the Clays and Limestones at Port-an-Righ, south 

 of Shandwick Bay, Ross-shire (Coralline Oolite). 



Belemnites sulcatus, Mill. 



abbreviates, Mill. 



Ammonites cordatus, Sow., varieties. 

 excavatus, Sow. 



Ammonites vertebralis, Sow. 



Reginaldi, ? Mor. 



plicatilis, Phil. 



Achilles, D' Orb. 



