A. Agassis — Notes from the Bermudas. 413 



arrested by the covering coat of Gorgonians, Millepores, Algae, 

 and Corallines as well as of the more massive corals found thriv- 

 ing upon the heads, patches, ledges and ledge fiats of the inner 

 and outer waters of the Bermudas. But these heads, ledges, etc. 

 do not as has been stated by former observers, owe their exist- 

 ence and their gradual increase to the corals, as they only form 

 a protecting veneer over their surface, viz : a coral growth and 

 not a coral reef. 



The so-called Serpulse reefs described before by previous 

 observers, are perhaps the most interesting structures of the 

 Bermuda reefs. They are most numerous off the south 

 shore, constituting miniature atolls, barrier and ' fringing 

 reefs apparently formed by the upward growth of Serpulse. 

 While Serpulse undoubtedly cover a great part of the sur- 

 face of the structures, yet Algse, Corallines, barnacles, mussels 

 and other invertebrates are found to be fully as abundant as 

 the Serpulse which in many cases play a secondary part. 

 In fact it would be as correct in some localities to call 

 them Algse or Coralline atolls. Neither the Serpulse nor the 

 Algse or other organisms have built up to any considerable 

 extent the vertical walls of the different kinds of diminutive 

 reefs so characteristic of the south shore. The Serpulse, 

 Algse, Corallines and other growths have only protected the sur- 

 face of the seolian rock ledges which form these structures from 

 the action of the breakers. They have not built up the 

 raised rims of the atolls, of the crescent or of the horseshoe- 

 shaped reefs, or the vertical walls forming the irregular con- 

 volutions and curves of the broader ledges. 



All these structures from a circular or elliptical atoll to a 

 barrier or fringing reef with all their possible modifications, 

 are due to the action of the surf and the wash of the sea in 

 eating away the surface of the mushroom-shaped rocks which 

 is either softer than the surrounding parts or is not protected 

 by the covering coat of Algse, Corallines or Serpulse. One can 

 off the south shore trace the whole process from the time when 

 the large fragments of shore seolian rocks fall by undermining 

 into the sea, until they are changed by the action of the surf 

 into mushroom-shaped ledges surmounted by pinnacles, next 

 into the stage when the pinnacle has in its turn been under- 

 mined and dropped alongside of the ledge to become the holding 

 ground of coral and other growth. The surface of the flat 

 ledge which formed the base of the pinnacle is now freely 

 acted upon by the breakers. According to the nature of the 

 upper crust and to the extent of protection given to it by the 

 covering coat of animal and vegetable life the sea acts upon 

 it and we have hollowed out atolls of diminutive size, crescent 

 or horseshoe-shaped structures as well as the curved, straight 



