CHEMISTRY: CLARKE AND STEIGER 
7 
from warm waters; a relation which was strikingly manifest in the analyses of 
echinoderms and alcyonarians and which has been amply verified by a con- 
siderable number of new analyses made since the original memoir was pub- 
lished. In other groups of organisms the same relation was suggested, but 
not actually proved to hold, for there were exceptions that needed explana- 
tion. In a series of eleven analyses of crustaceans (crabs, lobsters, shrimps 
etc.), the same variation in magnesia was strongly indicated, but with irregu- 
larities which appeared to require further investigation. It was conceivable 
that different parts of a shell or skeleton might differ in composition, or else 
that variations might be due to differences in age. It had already been 
found in the case of two sea urchins that the spines contained much less mag- 
nesia than the main body of the shells, but the question relative to age re- 
mained to be investigated. 
Through the kindness of Dr. H. M. Smith, director of the U. S. Bureau of 
Fisheries, the large claws of two lobsters {Eomarus americanus) from a single 
locality, Boothbay Harbor, Maine, were obtained, one from a small lobster, 
the other from a large specimen. The analyses gave the following results, 
after rejecting organic matter and water and recalculating to 100 % 
Si02 + (Al, Fe)20: 
MgCOs 
CaCOs 
CaS04 
Ca3P208 
SMALL LOBSTER 
LARGE LOBSTER 
0.19 
0.81 
6.02 
11.51 
80.52 
64.37 
1.29 
1.85 
11.98 
21.46 
100.00 
100.00 
The difference between these two analyses is very great, the large animal 
being much more highly magnesian and phosphatic than the small one. Un- 
fortunately, however, the actual sizes of the two lobsters were not given, 
and more precise data were evidently desirable. Accordingly Dr. Smith had 
fragments from three lobsters sent to us, all from the same station as the 
others, with definite figures as to^ length and weight. The fragments, more- 
over, in each case represented both the large claw and the carapace, so that 
variations in the individual as well as variations in age could be determined. 
The analyses, six in number, were as follows: 
1. Small lobster, length 8J inches, weight 10 ounces. 
2. Medium lobster, length llj inches, weight 2 pounds. 
3. Large lobster, length 16^ inches, weight 5i pounds. The claw is indi- 
cated by a, the carapace by b. 
