CALCAREOITS ALG«. 



Tliree of these algje are highly magiicsian; Ilalimeda and Galaxanm are not 

 Two analyses of alga^ by A. Schwager were published by J. Waltlu • 



53 



in 1885. There is 



also one by C."W. GiUnbel" and these three may be combined ui one tal)le, as lollows: 



1. Lithotlmmnium sp. Bay of Naples; A. Sch wager, analyst. 



2. Lithothamniuvi ramidosum. Bay of Naples; A. Schwager, analyst. 



3. Litholharmiium nodosum. Locality not stated; ('. W. Gumbel, analyst. 



Actual analyses ofalgx. 



SiO, 



AlA 



FeA 



MnO 



MgO 



CaO 



CO, 



PA 



Organic matter+HjO. 



Insoluble 



H,0 and loss 



1.59 



3.36 



.28 



Trace. 



1.90 



48.09 



39.87 



.5. 06 



1.91 



3.61 



.41 



Trace. 



3. OC, 

 45. 88 

 39. 41 



2.5.5 



2.66 



47. 14" 



40.06 



.06 



5. .57 



100. 15 



4.96 

 2.57 



99.85 



100. 00 



Reducing these to uniformity with oui- analyses we have the following table: 



Reduced analyses of algse. 



SiO„ 



(Al,Fe)o03 

 MgCOj."... 



CaCOj 



CajPA--- 



1.68 



3.83 



4.19 



90.30 



100. 00 



2.03 



4.26 



6.81 



86.90 



100. 00 



2.76 



6.06 



91.04 



.14 



100. 00 



In these analyses, all of LithotJiamnium, the percentage of magnesium carbonate is remark- 

 ably low. my this should be so is not clear, but it may be due to differences in he age of 

 the plants; that is, young specimens may have secreted less magnesia proportionally to lime 

 than older, more mature examples. This suggestion might well be tested by specia analyses 

 of properly selected material. Until that has been done the suggestion can carry little weight. 



Eleven partial analyses of LMothamnium, made by A. G. Hogbom,- assisted by K. Mauze- 

 lius, N. Sahlbom, and J. Guinchard, are curiously irregular. The percentages of magnesium 

 carbonate vary enormously, and with no apparent or even probable relation to temperatures. 

 The data given are as follows: 



Lilhothamnium 

 Lithothamniuni 

 Lithothamnium 

 Lilhothamnium 

 Litholhamnium 

 TAthothamnium 

 Lithothamnium 

 Litholhamnium. 

 Litholhamnium 

 TAthothamnium 

 TAthothamnium 



sp. Java Sea 



sp . Galapagos I slands — 



sp. Spitzbergen 



pohjmorphum. Kattegat. 



sp. Honolulu 



ramulosum. Naples 



sonferum. Arctic Ocean. 



sp. Bering Islands 



racemus. Naples 



sp. Bermuda 



glaciale. Arctic Ocean... 



CaCO,. 



72.03 

 83.60 

 84.83 

 74.22 

 84.01 

 63. 00 

 80.90 

 74.24 

 77.39 

 82.44 

 83.10 



MgCOj 



3.76 

 6.53 



8.67 



9.10 



9. :?9 



9.46 



9.56 



9.94 



11.33 



12.37 



13.19 



« Walther, J., Deut.whe. geol. Gesell. Zoitschr., p. 338, 1885. 



n Gumbel, C. W., K. bayer. Akad. Wiss. Abb., Math.-phys. Classc, vol. 11, p. 26, 1871. 



« Hogbom, A. G., Nciies .lahrb.. 1S94, Band 1. p. 2fi2. 



