A SUMMER RAMBLE AMONG THE HEBRIDES. 147 



of currents, induced we know not how, the innumerable 

 polypedes of the living surface were buried up ancl killed, and 

 then, for many yards, layer after layer of a calciferous grit 

 was piled over them. The fossils of the grit are few and ill 

 preserved ; but we occasionally find in it a coral similar to 

 the Astrea of the bed below, and, a little higher up, in an 

 impure limestone, specimens, in rather indifferent keeping, of 

 a genus of polypifer "which somewhat resembles the Turbi- 

 nolia of the Mountain Limestone. It presents in the cross 

 section the same radiated structure as the TurbinoliafunyiteS) 

 and nearly the same furrowed appearance in the longitudinal 

 one ; but, seen in the larger specimens, we find that it was a 

 branched coral, with obtuse forky boughs, in each of which, 

 it is probable, from their general structure, there lived a single 

 polype. It may have been the resemblance which these bear, 

 when seen in detached branches, to the older Caryophyllia, 

 taken in connection with the fact that the deposit in which 

 they occur rests on the ancient Red Sandstone of the district, 

 that led M'Culloch to question whether this fossiliferous for- 

 mation had not nearly as clear a claim to be regarded as an 

 analogue of the Carboniferous Limestone of England as of 

 its Lias ; and hence he contented himself with terming it 

 simply the Gryphite Limestone. Sir R. Murchison, whose 

 much more close and extensive acquaintance with fossils en- 

 abled him to assign to the deposit its true place, was struck, 

 however, with the general resemblance of its polypifers to 

 " those of the Madreporite Limestone of the Carboniferous 

 series." These polypifers occur in only the Lower Lias of 

 Skye.* I found no corals in its higher beds, though these 

 are charged with other fossils, more characteristic of the for- 

 mation, in vast abundance. In not a few of the middle strata, 

 composed of a mud-coloured fissile sandstone, the gryphites 



* See a paper by the Rev. P. B. Brodie, on Lias Corals, " Edinburgh 

 New Philosophic Journal," April 1857. 



