This page has been validated.
568
POPULAR SCIENCE MONTHLY.
make their way to this sea-washed platform. On the sea face the rock, which is an æolian limestone, is slightly raised above the general level of the floor, and is overgrown with nullipores and other corallines,
Fig. 25. The 'Intrepid.' From a photograph by L. J. Cole.
as well as non-calcareous algæ; and here serpulas, millepores and porites abound. Even at low tide this rocky platform is barely above water, and it is so honeycombed and porous that its surface is very
Fig. 20. North Rocks. From a photograph by Phelps Gage.
irregular. The flatter portions are covered here and there with patches of the curious Zoanthidæ. There are innumerable pools and channels all showing the greatest variety of color in the plant and animal life that clothes their sides and bottoms. Here in the pools and passages,
