18 



THE INORGANIC CONSTITUENTS OF MARINE INVERTEBRATES. 



24. Tropiometra carinata, Lamarck. From Pigeon Point, Tobago, British West Indies. Shoal water, near shore 

 temperature about 28° C. Received from Dr. Hubert L. Clark. According to A. H. Clark it ia probably T. picta 

 Analysis by R. M. Kamm. 



The actual analyses are given in the table below. Sulphates were determined in only one 

 of them, because the material was insufficient. 



Analyses of crinoid skeletons. 



The summation in most of these analyses is low. The deficiency is due mainly to inclosed 

 or adherent sea salts, an inevitable impurity, as was proved in the analyses of two separate 

 samples. In No. 15, 1.27 per cent of water-soluble salts was found, and in No. 17, 0.21 per 

 cent. These additions raise the summations to 99.66 and 99.54 per cent, respectively. 



