THE OPEN SEA BEACH 277 



Cape Sable there are beaches composed of silicious 

 sand and the same formation is met with on the 

 southeastern shore from Fort Lauderdale (the 

 northern limit included in this volume) to Cape 

 Florida. South of the two last mentioned capes 

 the beaches are either rocky, broken coral, coral 

 sand, or marl. The shores of southwest Florida 

 are wonderfully rich in marine life, especially in 

 mollusks. A little distance north of Cape Romano 

 at Sanibel Island there is the most amazing de- 

 velopment of marine shells I have ever seen. 



When the wind blows strongly toward the land 

 and the sea bottom is agitated for some distance 

 out, shells, often containing the animal, crus- 

 taceans, fish, sponges, and a great variety of life 

 are cast up on the shore. One of the strangest 

 of these creatures is the horseshoe crab (Limulus 

 polyphemus), a large crustacean that is seen from 

 May to midsummer, at which time it comes up on 

 the sand to lay its eggs near high water mark. 

 The outline of the body is nearly round, being 

 slightly drawn out behind : it has a long, spike-like 

 tail, and the general color is brownish or chocolate. 

 There is only one other species of the genus known 

 and it inhabits the Malay Archipelago. Limulus 



