42 



THE INORGANIC CONSTITUENTS OF MARINE INVERTEBRATES. 



The unusual proportion of magnesium carbonate in Argonaufa is confirmed by our analysis, 

 but the high phosphate in three of Biitschli's analyses is unlike anything in our series. Possibly 

 the calcium sulphate is really present in the hydrated form, that is, as gypsum, but that is 

 uncertain. However, it is not necessary to make that assumption, and to do so would com- 

 plicate the comparison of analyses. 



From the evidence now at hand and from many older data it is clear that molluscan shells 

 consist almost entirely of calcium carbonate with quite insignificant impurities. The only 

 notable exception is Argonauta, which contains 6 per cent of magnesium carbonate, but the 

 paper nautilus has no importance as a contributor to the marine sediments. The molluske 

 generally are of immense importance, a fact to which their fossil remains abundantly testify. 

 In composition they resemble the corals and millepores, so much so that an analysis from one 

 group might readily pass for an analysis from another.^' 



CRUSTACEANS. 



The 19 crustaceans analyzed in the course of this investigation fall into two distinct groups. 

 First, the barnacles, which have shells composed mainly of calcium carbonate with very little 

 organic matter. Second, a group of the more familiar crustaceans, such as crabs, shrimps, and 

 lobsters. These have shells containing notable amounts of calcium phosphate and much 

 organic matter. The analyses of the first group cover the following species: 



1. Lepas anati/cra T/inn^. Florida. 



2. Lepas anserifem I.inn6. Woods Hole, Mass. 



3. Mitella polymerus Sowerl.y. Pacific Grove. Calif.; latitude. 36° 36' N.; longitude, 121° 55' W. 



4. Balanus hameri .\scanius. Georges Bank, east of Cape Cod, Mass. 



5. Balanus amphitrite nivctis Darwin. Cape May, N. J. 



6. Balanus ehurncus Gould. Smiths Creek. Potomac River. Md. 



7. Scnlpe.llutn rer/ium Wj'\dlle Thomson and Hoek. Albatrnsx ,=tation 3342; off Queen Charlotte Islands; latitude, 

 52° 39' 30" N.j longitude. 132° 38' W.; depth of water, 2,906 meters; bottom temperature, 1.8° C. 



The analyses are as follows: 



Analyses of barnacles. 



SiO, 



(Al.Fe^jO,. 



MgO 



CaO 



P,0, 



Ignition 



CO2 needed.. 

 Organic, etc. 



0.04 



.19 



1.14 



52. 33 



Trace. 



44.50 



98.20 



42.37 



2.13 



0.04 

 .56 

 .86 



52. 53 

 .34 



43. 90 



98.23 



41.82 



2.08 



0.08 



.30 



.94 



50.83 



Trace. 



46. 18 



98.33 



40.97 



5.21 



0.03 

 .14 

 ..35 



53. 57 

 .00 



44. .39 



98. 18 



42.47 



1.92 



1.99 



.68 



.73 



50.09 



Trace. 



44.84 



98.33 

 40.16 



4.68 



0.39 



.22 



!76 



53.23 



Trace. 



44.28 



98.88 



42.67 



1.61 



\ 0.73 



1.03 

 52. 65 

 Trace. 

 4-1.79 



99.20 



42.48 



2.31 



Reduced analyses of barnacles. 



" For additional data see Schmelck, L., Norske Nordliavs Exped., No. 2S, p. 129, 1901. Fourteen analyses of moUiiscan shells are given, ot 

 the genera Bvccinum, Astarte, Ncptunea, and Pecten, all from the North Sea. The highest percentage of magnesium carbonate found was 0.7S, 

 the lowest 0.2t>. For ten complete analyses of oyster shells see Chatin, A., and Muntz, .V., Compt. Rend., vol. 120, p. 531, 1S95. For eleven analyses 

 of land shells see an inaugural dissertation by A. Doring, Gottingen, 1872. Several determinations of magnesium carbonate, maximum I per cent, 

 are given by G. Forchhammer in Neues Jahrb., 1852, p. 854. 



