Tuesday December 26th 1911. Marathon, Fla. Walked rest of Marathon on the track for 1/2 miles and collected shells only of small dredger from the sounds and bags about the keys, probably one mile north of Marathon, hardly more than 5 feet above the sea. The elevated coral reef profile is here seen anywhere in Key Biscayne. Great heads of various reefs may be seen in their position of growth in size up to 3 feet across. These are all hemi- pheric heads and one sees no star-borne coral among them. Reefs are exceedingly rare. All of this coral reef is free of solution holes and is undermined by the sea and blocks of 5 foot across and 1 foot thick are thrown upon the shore by the storms. Small islands of it still remain but are being carried away by the solvent action and mechanical action of the sea. It's dark material to walk on. Adjacent in the sea the bottom is full of Halimeda and other calcareous secreting algae. Here and there one sees an actinarian and small head of coral reminding of Orbicella. In this grain there is also Porites as I picked of some.