AGASSIZ : BERMUDAS. 235 



of low seolian hills. A further slight subsideuce would change them 

 into shallow harbors by the rushing in of the water over the lowest of 

 the dividing saddles. A similar low tract extends to the south of Gov- 

 ernment House between it and Hamilton, with an outlet into Boss Bay. 



DISTRIBUTION OF THE CORALS. 



The Bermudas are the most northerly limit ^ where reef-building 

 corals are known to occur, unless we can call coral districts areas where 

 Astrangia, Primnoa, and other northern types, like Caryophyllia and 

 Lophohelia, are to be found. 



The absence of Madrepores, to which Thomson called attention, is 

 very striking. There are thus wanting the very elements to supply the 

 bulk of the material broken off and thrown up by the sea to accumulate 

 as beaches or islets. 



It is interesting to note that the littoral marine fauna of the Bermudas 

 is the same as the shallow water fauna of the West Indies, and that its 

 existence here is one of the finest examples of the effects of great oceanic 

 currents in shaping the geographical distribution of animals the em- 

 bryos of which are pelagic a sufficient length of time to be transported 

 to this their northern limit from the Bahamas and other parts of the 

 West Indies. During my stay at the Bermudas, every day when the 

 wind blew from the southwest or west the common West Indian 

 Physalia appeared in great numbers. 



Besides marine animals, floating masses of wood coming from the West 

 Indies are frequently stranded on the shores of the Bermudas, these 

 sometimes carrying fragments of rooks. A large ellipsoidal mass of 

 floating pumice, measuring eleven inches in length, was picked up off the 

 south shore by the Hon. Archibald Alison. A similar float, thrown up 

 on the south shore, is preserved in the Museum of the Government 

 Building. This piece is filled with red earth. 



1 The minimum temperature of the surface of the sea occurs in January and 

 February, when it varies between 59° and 63°. In March it varies from 62° to 66°. 

 In April its maximum has already risen to 71° ; in May the maximum is 76°, 

 minimum 70° ; in July the minimum is 70°, maximum 82^° ; in August the maximum 

 is 85°, minimum 82.^° ; in September the maximum is 8.3°, and the minimum 75°. 

 The temperature tlien falls rapidly from 69° and 74° in October, down to 61° and 

 65° in December. The minima are remarkably low temperatures for a coral reef 

 district. The above data were kindly furnished me by Mr. John C. Watlington, of 

 Hamilton. 



