REPORT OP THE STATE PALEONTOLOGIST 1902 895 



Such is the peculiar fauna, and in the study of it we are led to 

 seek (1) the cause of this dwarfing, (2) the reason for the lack of 

 uniformity of effect, (3) the length of time the fauna has been 

 acted on by dwarfing agents, (4) the modifications effected both 

 in shape and size. 



In considering whether water impregnated with iron and 

 sulfur variously oxidized can dwarf without annihilating a * 

 fauna, I may cite other instances of faunas similarly affected 

 by the medium. The oolitic hematite iron ore band of the Clin- 

 ton beds extends from central New York westward to Wisconsin 

 and south to Alabama, is at many localities highly fossiliferous, 

 and according to Smyth 1 it was laid down in water carrying an 

 excess of iron in solution. Observations made by the writer 

 on the fossils of this layer obtained at Rochester N. Y. show 

 that these species have an average of about one third the diam- 

 eter of the same species in the beds just above and below. The 

 dwarfing, in this case, can not be attributed to anything but 

 the iron in the water, acting as an unfavorable environment. 

 Linney 2 notices the same dwarfing in this layer in Kentucky. 

 To verify this dwarfing effect of iron in solution or suspension, 

 experiments were made on small fishes, tadpoles and snails 

 in aquarium water saturated with iron; and kept beside control 

 aquariums, the fish, etc., in both cases being fed all they would 

 take. After eight months in this iron water, the fish and tad- 

 poles had lost from 3 mm to 5 mm in length. 3 Their habits had 

 also undergone considerable change. 4 It is well known that cer- 

 tain species of fishes living in the freshened Baltic sea are much 

 smaller than the same species in the Arctic ocean. 5 Herbst 6 and 

 others, experimenting on embryos in water with various chem- 

 icals, get dwarfed and abnormal results; these however have not 

 lived on to adult condition. In all these cases, and in many 



1 Am. Jour. Sci. 1892. 143 : 487. 



2 Report of Bath county, Ky. 



3 This experiment was carried on by Messrs Burrows, A. C. Kretchmar and 

 Southgate in the biologic laboratory of Amherst College. 



4 While the results in the above experiment are not large, they show the dwarf- 

 ing effects of iron; and on animals born in the iron waters, the effect would be 

 much greater, as in embryonic life they are more sensitive. 



5 See Gunther. Introduction to the Study of Fishes, p. 204. 



"Zeitschr. f. Wissenschaftl. Zoologie. 1892. v. 55. See also Wilson. The 

 Cell. 1896. p. 323. 



