entrance of Oyster Bay, the water is uni- 

 formly 15 to 18 feet deep at low tide. Im- 

 mediately below Oyster Bay entrance is a 

 bar with only 6 to 10 feet of water at low 

 tide. At the eastern end of this bar is a 

 channel 72 feet deep. Outside the bar the 

 water deepens steadily towards the middle 

 of the sound. 



The steep sides of the harbor are piles of 

 glacial drift, full of clay, siliceous sand, 

 gravel and boulders of varying size. This 

 determines the prevailing chai-acter of the 

 shore line, sandy or gravelly beaches with 

 boulders extending into deep water and most 

 abundant at the base of the worn-ofF bluffs. 



Mud flats are common, but for the most 

 part underlaid by sand at a depth of one to 

 three feet. A mud flat extends from parts 

 of the sand spit at the level of mean low 

 tide. No rock occurs in place, but on many 

 headlands the accumulated boulders at the 

 base of the bluffs form an extensive rock- 

 work. At intervals the shore line of the 

 harbor is diversified by salt meadows, partly 

 enclosed salt ponds and shallow ' harbors ' 

 and bays. 



THE FAUNA ABOUT COLDSPRING HARBOR. 



The situation of the laboratory is unique 

 in its combination of immediately accessible 

 faunas of the sea, fresh- water and wood- 

 land, all very rich in individuals and spe- 

 cies. Some of the commoner or more inter- 

 esting forms may here be enumerated. The 

 list may be prefaced with the statement 

 that, owing to the fact that the Harbor is so 

 nearly an inland sea, there are few strag- 

 glers in the marine fauna ; what one finds 

 belongs to the place — its presence is deter- 

 mined by the local environment. 



