36 



THE INORGANIC CONSTITUENTS OF MARINE INVERTEBRATES. 



The reduced analyses were computed by us from Schwager's data. 



In Flustra folkicea from California H. W. Nichols -* found 1.23 pendent of magnesium car- 

 bonate, and in a bryozoan from Bermuda 5.35 per cent. Several similar determinations by G. 

 Forchhammer -" on other Bryozoagave less than 0.6 per cent. The other constituents of the 

 organisms were not determined, and the figures given for magnesium carbonate therefore have 

 little present value. , 



From the evidence now at hand no broad general conclusions can be drawn. That the 

 magnesian content of the Bryozoa varies widely, however, is clear, being lowest in the com- 

 pact coralline forms and highest in the fernlike varieties. Even this conclusion needs to be 

 verified by a much larger series of analyses. 



BRACHIOPODS. 



A few analyses of bracliiopod shells already on record show that they fall into two chemi- 

 cally distinct groups — one calcareous, the other highly phosphatic. This conclusion is sup- 

 ported and emphasized by the new data obtained by us, which also bring out some minor 

 peculiarities that seem not to have been previously observed. For our material we are indebted 

 to Dr. W. H. Dall, who selected typical specimens from among the duplicates in the United 

 States National Museum. First in order come five brachiopods representing as many genera 

 in the calcareous group. The analj^ses are as follows: 



1. Terebratula cubensis Pourtales. Coast of Florida. 



2. Terebratulhia septentrionalis Gray. Eastport, Maine. 



3. Laquetis californicus Koch. Esteros Bay, Calif. 



4. Rhynchonclla psitlacea Gmelin. Shetland Islands. 



5. Crania anomala MilUer. Coast of Norway. 



Analyses of calcareous brachiopods. 



SiO, 



(Al,Fe)A 



MgO 



CaO 



SO3 , 



P=0, 



Loss on ignition ... 



CO2 needed 



Organic matter, etc 



0.50 



.14 



.62 



51. 79 



.66 



Trace. 



45. 28 



98.99 



40. 55 



4.73 



0.18 



.47 



.32 



54. 48 



.21 



Trace. 



44.46 



100. 12 



42.91 



1.55 



0.14 

 .23 

 .23 



53. 76' 

 .31 

 .17 



44.81 



99.65 



42.16 



2.65 



0.21 



.26 



3.90 



48.67 



.97 



.25 



45.38 



99.64 



40.88 



3.52 



Rejecting organic matter and recalculating to 100 per cent, the analyses assume the follow- 

 ing rational form: 



Reduced analyses of calcareous brachiopods. 



» Nichols, H. W., Field Columbian Mus. Pub. Ill, p. 31, 1906. 



» Forchharamer, G., Neucs Jahrb., 1?52, p. 854. 



