THE LIFE OF THE SEA-SHORE. 149 
and strong spines, are nearly always to be found. Beautiful 
creatures as they are, it is not wise to attempt to handle 
them, for the spines are strong and sharp. Occasionally 
stranded in the pools, one may find an Angler or Fishing 
Frog, a curious, ugly creature, with dangling filaments or 
lures on its head. Its proper home is the sandy bottom, 
where it lies half buried, with the dangling lure only 
exposed. The little fish come up to see what the strange 
thing may be, then the great mouth opens, and the little 
fish pay the penalty of rash curiosity, and are seen no more. 
Much more common on the rocks are the flat-fish or soles, 
which are also sand-loying forms, are marked so as to 
closely resemble the sand, and curiously flattened from side 
to side, so that the surface upon which they rest is not 
really the lower but one of the sides. Another not un- 
common shore form is the viviparous blenny, interesting 
because it does not lay eggs, but gives birth to living 
young. 
3. All these forms live habitually about or among the 
rocks, and constitute with many others what I have called 
the floating population; but there are others which only 
appear at certain seasons, often in vast numbers, and then 
disappear again almost completely. These I call the 
occasional visitors. For example, in the early part of the 
year, in February and March, the rocks at various parts of 
the Firth of Forth are literally whitened by countless 
numbers of a little sea-slug (Doris bilamellata) and its 
spawn. I do not say that it is entirely absent at other 
seasons of the year, but it is certainly not abundant. It 
must, therefore, be a migratory form, and live usually beyond 
low-tide mark. Similarly, many other sea-slugs, and among 
them the more delicate and beautiful forms, are only found 
during their spawning seasons, and then apparently disappear 
completely. The large cuttle Ommastrephes also appears 
often in numbers in early spring, when it lays its eggs at 
the margin of the rocks, and is then not found again till the 
next spring. It is, however, perhaps the fishes which show 
this phenomenon in the most striking way, for they are 
often powerful swimmers, and the migrations may be ex- 
tensive. 
