568 The American Naturalist. [July, 
SUPPLEMENTARY INVESTIGATION AT 
TICK ISLAND. 
By CLARENCE BLOOMFIELD Moore. 
In the February, 1892, number of the American NATUR- 
ALIST, I gave an account of certain investigations made by 
me at Tick Island, Volusia Co., Florida. The readers of that 
article will recall that into the great sand mound at that place 
numerous trenches and shafts were made, resulting in the 
discovery of a number of objects of interest archeologically, 
and the formation by me of a theory as to the construction of 
the mound. This theory has not in any way been modified 
by a supplementary investigation continued with a party of 
seven assistants through January 15th, 16th, 18th, 19th, 1892. 
The mound is built upon a circular heap of shell converg- 
ing to an apex at the center. This heap was probably 
brought from neighboring shell deposits or a low heap already 
formed was used for the purpose. I am inclined to believe, 
however, that the shell was brought with a view to the forma- 
tion of a solid base in the swamp, since irregular ridges and 
elevations of shell do not extend beyond the margin of the 
mound as is so often the case where sand mounds have been 
piled upon previously existing shell heaps. It will be 
remembered that a ridge of pure white sand with sloping ends 
ran north and south almost through the mound, this ridge 
being covered with brown sand having at times a certain 
admixture of shell,and that this covering of brown sand, com- 
paratively small at the extremities of the ridge, attained great 
thickness on its sides to the east and west thus completing 
the conical shape of the mound. 
On the western side of the mound, beginning at the mar- 
gin of the base, was made a diverging trench, 8 ft. in breadth 
at the start, 54 ft. in length, or 4 ft. beyond the center of the 
mound. At 44 ft. from the starting point the breadth of the ` 
trench was 14 ft. and its depth 10 ft. From this point to the 
end the breadth of 14 ft. was maintained to a depth of 6 ft. 
