THE LAKE OF STENNIS. 



Sandstone, and be scarce missed when away : nay, for everyyear 

 during which man has lived upon earth, it is not improbable 

 that the Pterichthys and its contemporaries may have lived 

 a century. Their last hour, however, at length came. Over 

 the dark-coloured ichthyolitic schists so immensely developed 

 in Caithness and Orkney there occurs a pale-tinted, unfossi- 

 liferous sandstone, which in the island of Hoy rises into 

 hills of from fourteen to sixteen hundred feet in height; and 

 among the organisms of those newer formations of the Old 

 Ked, not a species of ichthyolite identical with the species 

 entombed in the lower sehists has yet been detected. In the 

 blank interval which the arenaceous deposit represents, tribes 

 and families perished and disappeared, leaving none of their 

 race to succeed them, that other tribes and families might 

 be called into being, and fall into their vacant places in the 

 onward march of creation. 



Such, so far as the various hieroglyphics of the pile have 

 yet rendered their meanings to the geologist, is the strange 

 story recorded on the three-barred pyramid of Stromness. I 

 traced the formation upwards this evening along the edges 

 of the upturned strata, from where the Great Conglomerate 

 leans against the granite, till where it merges into the ich- 

 thyolitic flagstone ; and then pursued these from older and 

 lower to newer and higher layers, desirous of ascertaining at 

 what distance over the base of the system its more ancient 

 organisms first appear, and what their character and kind. 

 And, embedded in a grayish-coloured layer of hard flag, 

 somewhat less- than a hundred yards over the granite, and 

 about a hundred and sixty feet over the upper stratum of 

 the Conglomerate, I found what I sought, — a well-marked 

 bone, — in all probability the oldest vertebrate remain yet 

 discovered in Orkney. What, asks the reader, was the cha- 

 racter of this ancient organism of the Palaeozoic basin ? 



As shown bj its cancellated texture, palpable to the naked 



