114 THE OLD RED SANDSTONE. 
oryctology of the older rocks — little, indeed, of that of the 
Old Red Sandstone, in its proper character as such; and with 
no such guiding clew as has since been furnished by Agassiz, 
and the later researches of Mr. Murchison, the writer of the 
appendix had recorded as his ultimate conclusion, that “ the 
middle schistoze system of Caithness, containing the fossil 
fish, was intermediate in geological character and _ position 
between the Old and New Red Sandstone formations.”” ‘The 
ichthyolites of Gamrie he described as resembling those of 
Caithness ; and I at once recognized, in his minute descrip- 
tions of both, the fossil fish of Cromarty. ‘The mineralogical 
accompaniments, too, seemed nearly the same. In Caithness, 
the animal remains are mixed up in some places with a black 
bituminous matter like tar. I had but lately found among the 
beds of the little bay a mass of soft adhesive bitumen, her- 
metically sealed up in the limestone, which, when broken 
open, reminded me, from the powerful odor it cast, and which 
filled for several days the room in which | kept it, of the old 
Gaulish mummy of which we find so minute account in the 
Natural History of Goldsmith. ‘The nodules which enclosed 
the organisms at Gamrie were described as of a sub-crystalline, 
radiating, fibrous structure. So much was this the case with 
some of the nodules at Cromarty, that they had often reminded 
me, when freshly broken, though composed of pure carbonate 
of lime, of masses of asbestos. ‘The scales and bones of 
the Caithness ichthyolites were blended, it was stated, with 
the fragments of a “‘ supposed tortoise nearly allied to trionyx ;” 
one of the ichthyolites, a Dipterus, was characterized by large 
scales, a double dorsal, and a one-sided tail; the entire lack 
of shells and zoophytes was remarked, and the abundance of 
obscure vegetable impressions. In short, had the accom- 
plished writer of the appendix been briefly describing the beds 
