42 The Scottish Naturalist. 



position in that series as the brick clay at Kilchattan, in the 

 Clyde basin, described by Professor Geikie,* who says that this 

 red brick clay sometimes dwindles down to only a few inches 

 in thickness, but is almost always found between the shell-clay 

 and the hard-till. Round the whole of the coast of Bute and 

 on the Cowal shores, the invariable layer of fine, stoneless, 

 and unfossiliferous clay is intercalated between the shell-bearing 

 bed and the coarse, stiff boulder clay. The absence of shells 

 is not less singular : after not a little inquiry, I have been 

 unable to ascertain the discovery in it of a single organism. 



Of the shells found in those clays on both sides of Scot- 

 land, a number are boreal or arctic species, but some of 

 them are also southern forms. The former have now either 

 moved out to the deeper water of the ocean, or migrated further 

 north, according as each finds an environment most suited to its 

 nature. All the other species are still living in the surrounding 

 seas : a few of these may have altered somewhat in size, or in 

 the thickness or thinness of shell ; otherwise they are unchanged 

 since the close of the Glacial period. 



On the east coast, shells have been met with, although rarely, 

 in brick clay at Tyrie, near Kinghorn ; with this exception, 

 shells may be said to be unknown in any of the brick clays 

 along the coast, from the Tay to the Tweed — the Elie clay 

 containing shells is a different formation. Beyond the Tay they 

 have been found in clay at Errol, at Montrose sparingly, in 

 Aberdeenshire, and in several places farther north. 



In 1863 Professor Allmanf obtained a star-fish from a 

 brick clay near Dunbar ; he named this new species Ophio- 

 lepis gracilis, and described it at a meeting of the Royal 

 Society of Edinburgh. Shortly after this, specimens of the same 

 species were found in brick clay at Seafield, near St. Andrews. I 

 directed attention to these in the " Annals and Magazine of 

 Natural History," January 1864. Dr. Howden has also procured 

 this star-fish from clay near Montrose. Since 1864 although 

 star-fish have turned up now and again in the Seafield clay, it 

 was not until recently that they could be said to be at all nume- 

 rous. Last autumn the workmen in digging the clay at a 

 depth of about eleven feet from the surface and some thirty 

 feet above the sea, struck upon a part of it where there was a 

 thin parting of sand that contained these star-fishes in consider- 



* Glacial Drift of Scotland. + Proceedings Royal Society, Edin., Vol. 5. 



