48 Fietp CotumB1AN Musgeum—Geotoey, Vot1. ITI. 
organic matter in considerable quantities, so that the ratio of magnesia 
to lime carbonates in the skeletons alone is higher than indicated by 
the percentages obtained for the dried specimens, which latter percent- 
ages are the ones in the accompanying table. 
MAGNESIUM CARBONATE CONTENT OF THE SKELETONS: OF VARIOUS 
MARINE CALCAREOUS ORGANISMS. 
Analyses by the author in Roman type; those by other analysts 
in italics. 
No. Mus. No. Mg CO, 
-ALCYONOID CORALS. ie 
Li aay Eunicea tourneforti, Bahamas, 2.78 
2 EOF Plexaurella dichotoma, Bahamas, 2,11 
3 — Isis hippurts,* 6.362 
4 ——  Corallium nobile,* 2132 
5 — Corallium rubrum, Mediterranean,t 0132 
6 314  Tubipora musica, Singapore, — 3.83 
ZOANTHOID CORALS. 
rDipalele Coeloria daedolea, Abyssinia, 0.35 
a Astraea cellulosa,* 0.542 
ao Siderastraea sp., Bermuda,} : 2.42 
BRYOZOA. 
1o6©6r0o41~ -~—sCw FF lusstra foliacea, California, 1.23 
tr ——  Eschara foltacea,* 0.146 
12 ~iove. “Garapholasicp.. 3.99 
13 ———  Bryozoan? Bermuda, bees 
in 6 57. Lithoramnion racemus; Bahamas, 0.65 
15 —— Myrtazoon truncatum,* 0.455 
16 ——  Heteropora abrotanotdes,* 0.352 
17 ——  Frondtpora reticulata,* 0.596 
PELECYPODA. 
18 2879 Teredo gigantea, Indian Ocean, ; 0.00 
19 ——.. Osirea sp.;§ 0.3 
20 —— Modiola papuana,* 0.705 
21 ——— Pinna nigra, Red Sea,* I.000 
GASTROPODA. 
22 G1331 Vermetus sp., Bermuda,|| 0.35 
* Analysis by J. G. Forchhammer: 1849. Bidrag til Dolomitens Dannelshistorie: Oversigt over 
det Kongelige Danske Videnskab. 1840, pp. 83 — 06. 
t+ Polished material from a necklace. 
+ Analysis by L. G. Eakins; Bull. U.S. G. S., No. 228) p. 308. 
§ Analysis by Sharples? Dana: Manual of Geology, p. 72. 
| The incrustation of specimen shown in Plate XXVI, Fig. s. 
