170 



BULLETIN: MUSEUM OF COMPAEATIVE ZOOLOGY. 



Salt Key Bank, oolite 



Sombrero ileposits (P2O5 39.12) 



Coralline Bottom, Tortugas 



Senote limestone near Merida 



Diamond Head, Sandwich Islands, coral rock 



Kohuku Bluff, 



Kohuku Beach, " " sand 



Honolulu Eeef, coral rock 



Prison Knob, Honolulu (elevated coral) 



Waianea (hard ringing limestone) 



Modern chalk, Oahu 1 



( SiOa 33.25, Al.Pg 19.13, Fe.^ 10-71 ) f 

 Lava soil bedded with coral near Pearl River ) 



(SiO. 46.22, ALOg 19.16, FeA 12.94) \ 

 Same from Diamond Head I 



(SiO.. 32.83, AI2O3 12.12, FeaOg 11.52) J 



CaO 



53.54 

 51.15 

 46.45 

 54.87 

 44.82 

 51.09 

 49.34 

 46.52 

 52.67 

 50.69 



11.37 



1.72 



12.20 



CO2 



43.87 

 3.47 

 43.40 

 43.89 

 40.81 

 43.64 1 

 44.33 

 40.59 

 42.81 

 43.96 



MgO 



0.71 



trace 



5.15 



0.64 



5.32 



2,50 



4.60 



2.45 



0.42 



2.98 



11.09 — 



Moisture 

 1.13 

 7.55 

 2.73 

 0.11 

 1.86 

 0.79" 

 0.40 

 2.75 

 1.24 

 0.46 



9.84 



0.00 2.24 16.84 

 11.41 11.70 5.30 



The Rocks of the Bahamas. 



The characteristics of the seoliaii rocks of the Bahamas have been noted 

 in the description of the different islands of the group. They vary from a 

 fine-grained compact ooUte to a coarse-grained rock composed either of 

 rounded or of small angular fragments, according to the condition of the 

 fragments of the sand from which the Eeolian hills were composed. These 

 rocks vary according to the conditions to which they have been subjected, 

 and which often greatly alter their aspect. They become more or less 

 hardened or covered with a hard ringing crust when exposed to the action 

 of the sea or of the rains, or to the decomposing effects of the acids gen- 

 erated by the decomposition of vegetable matter. Sufficient time has not 

 elapsed since my return from the Bahamas and Bermudas to report 

 more in detail regarding the composition of the rocks and bottoms of 

 these regions. But I hope to return to this subject, and present the 

 results of the examination of the rocks now making by Professor Wolff. 



SOME RECENT VIEWS ON THE THEORY OF THE 

 FORMATION OF CORAL REEFS. 



It may not be out of place to pass rapidly in review some of the points 

 relating to the theory of the formation of coral reefs which have been 

 brought forward in the discussion of the subject in the new issue of Dar- 



^ Trace of organic matter. 



