THE COMMERCIAL SPONGES AND THE SPONGE FISHERIES. 427 
attachment for sponges and other sessile marine organisms. In the same way 
on the Bay grounds the bottom is denuded by currents in the channels, as at the 
north end of Hog Island, and on the Buoy grounds above Anclote Key, while 
offshore there are rugged outcroppings of rock rising above the surrounding sand. 
It is upon these ‘‘spots of bar,”’ as the spongers call them, insignificant in area as 
compared with the adjoining stretches of sand and mud, that the sponges occur 
in greatest abundance, attached to the rocky floor of the sea. 
Occasionally they grow on sea feathers, which in turn are anchored to the 
bottom, or on mangroves, and considerable numbers are often found in the grass 
or in saucer-shaped sandy depressions surrounded by grass. ‘Their occurrence 
in the latter places apparently contradicts the statement that they do not grow 
on grass or sand, but the contradiction is apparent rather than real, as they have 
been in all cases originally attached, but either in the operation of sponging or 
by wave action have been torn loose, and rolling freely over the bottom at the 
mercy of the waves have finally been entrapped in the tangle of vegetable growth. 
Such sponges are generally almost spherical, have no “‘root,’’ and the surface is 
uniformly smooth from friction on the bottom and harsh from the excessive 
inclusion of sand grains. They are known to the spongers as ‘‘rollers”’ or 
“rolling johnnies” and are often found in groups in sandy depressions in grassy 
bottom called ‘“‘turtle sets” from the erroneous supposition that they are made 
by turtles. 
BAY GROUNDS. 
The Bay grounds, which formerly held a secondary place commercially, now 
yield practically the entire production of Florida sponges, the Key grounds 
furnishing hardly 9 per cent of the sheepswool sponges and less than 13 per cent 
of all kinds. The Bay grounds begin at or near Johns Pass, a few miles north of 
Tampa Bay, and extend without material interruption as far as St. Marks, a . 
distance of 160 miles. As known at the time of the introduction of the diving 
machine, this ground extended from a depth of 10 or 15 feet to from 7 to 12 
fathoms 20 to 4o miles from shore, but although sponges had been seen in the 
greater depths, no sponging had been done in more than 8 fathoms owing to the 
limitations imposed by the methods employed. Grass and a few sheepswool 
sponges were taken in less than ro feet of water, especially in the early days of the 
fishery, but the bulk of the product was from between 20 and 35 to 4o feet, 
though in 1902, owing to unusually favorable conditions, a heavy catch of fine 
sponges was made in water as deep as 45 or 48 feet. Several persons had 
reported seeing sponges in 20 fathoms, and it is stated that on at least one 
occasion a sponge was brought up from 17 fathoms on a fish line. 
In 1905 the area of the known sponge beds in the Bay grounds was about 
3,400 square miles. Since then the operations of the divers, who in a few cases 
