ADDENDA. 



P. 18. A calcareous crust of recent origin, in some cases occu- 

 pies depressions in the exterior surface of the hills of coral sand- 

 rock. These hills are of beach origin, and although 50 or 60 feet 

 thick, consist throughout of the coral rock, having a sandy texture and 

 generally laminated. There is nothing crust-like in their structure, any 

 more than in the red sandstones of the Connecticut river. We are led 

 to make this explanation by a wrong use made of the facts by a recent 

 writer. 



\A 



P. 57. The following are fig- 

 tires of other crystals of gypsum, 

 which were crystallized from a 

 drop of sea-water, under a micro- 

 scope, while the author was ex- 

 amining some minute oceanic 

 Crustacea, in the Atlantic, latitude 11° S., longitude 12° West. 



P. 58. The following is the mean of several recent analyses of the 

 sea, in the Laboratory of L. Mulder (J. f. pr. Chem., lv, 499, 1852), 

 together with analyses by Figuier and Mialhe, Regnault, and Riegel. 

 The waters were those of the Atlantic or North Sea. 



Chlorid of Sodium, 



L. Mulder. 



78-5 



F. & M. 



78-9 



Regnault. 

 76-5 



Riegel 



75-2 



" Magnesium, . 

 Sulphate of Magnesia, 

 " Lime, 



9-4 

 64 



4-4 



8-6 



7-7 

 3-7 



102 

 65 



4-0 



9-0 

 60 



7-6 



Chlorid of Potassium, 



10 



0-25 



2-0 



0-9 



Bromid of Magnesium, 



017 



0-4 



01 



05 



Carbonate of Lime, 



0-04 



04 



01 



05 



Silica, . 



0-009 



0-05 







Ammonia, 



013 









P. 61, 97. The temperature 66° F., stated 

 seas, is nearly, if not quite, the extreme temperature. 

 coldest month along the boundary is 68° F. 



as limiting coral reef 



The mean of the 



P. 106. The absence of coral from the coast of China is due to the 

 temperature of the waters. The author has found, on further investi- 

 gation, that on no part of the coast of China the sea has the temperature 

 of 68° F. in winter. The winter line of 68° bends northward on ap- 

 proaching the coast of China, and includes the island of Loochoo ; but 

 it is then deflected abruptly to the south and terminates at latitude 15° 

 N., on the coast of Cochin China. 



