ON THE ICTIS OF DIODORUS SICULUS. 323 
period, unless measures are taken to form an arti- 
ficial barrier against the incursions of the ocean, 
a channel will be formed, which will divide it into 
two smaller islands. 
Facts like these go far to prove that the Cassi- 
terides of the ancients were no other than the 
Scilly Islands of our own time ; and that the dif- 
ference between these islands, in their past, and 
in their present state, is attributable to subsidence, 
and to atmospherical and oceanic agency. The 
process by which so extraordinary a change has 
been effected, is precisely similar to that which 
has been in operation along the Cornish coast, 
and to which the disappearance of the Ictis of 
Diodorus may not unreasonably be attributed. 
We arrive, then, at the conclusion, that such 
an island once actually existed; that it was neither 
the Isle of Wight, nor St. Michael’s Mount, nor 
a portion of the present main land; but that the 
small group of rocky islands, called the Long- 
ships, are probably the summits of its more ele- 
vated parts, the rest being either submerged, or 
swept away; and that “the neighbouring islands,” 
to which the same peculiarity attached as to 
