850 NATUKAL HISTORY OF AQUATIC ANIMALS. 



the two groups with any certainty." This subspecies occurs at the Bahama Islands and Florida. 

 Three varieties are classed with it by Professor Hyatt, yosaypiniformis, from Nassau ; fnnca- and 

 elongate, from Biscayue Bay and Key West, Florida ; the range in depth is from two i'eet of water 

 at low tide to thirty feet or more. 



This constitutes the second grade of American Sponges, and is very abundant. Although 

 selling at a much lower price than the Sheepswool it forms an important article of commerce. 

 The Mediterranean grade corresponding with it is the so-called Zitnocca Sponge. 



239. INJURIOUS SPONGES. 

 THE BOEING SPONGE CLIONA SULPHUREA, Verrill. 



This is a common species of siliceous Sponge, which ranges along our Atlantic coast, from 

 Cape Cod to South Carolina, in from one .to fifteen fathoms of water. It begins to grow on 

 mussel, clam, or oyster shells, mostly on dead, but also on living specimens, into which, when 

 still very young, it excavates numerous burrows. " As it grows, it penetrates the shell in every 

 direction, forming irregular holes and galleries, which continue to grow as more and more of the 

 substance of the shell is absorbed, until the shells are reduced to a completely honeycombed, 

 brittle mass, or a mere skeleton. Finally the Sponge begins to protrude from the surface, and 

 grows up into mammiliform masses, or small rounded crusts, which continue to grow and spread 

 in every direction, until finally they form masses six or eight inches in diameter. . . . Owing 

 to the remarkable boring habits of this and other allied Sponges, they are very important in the 

 economy of the sea, for they are the principal agents in the disintegration and decay of the shells 

 that accumulate over the bottoms, thus performing the same function in the sea that fungi and 

 insects perform on the land." ' 



There is no question but that the offices of this Sponge are mainly for good, as stated above; 

 but they often attack living shells, burrowing into them as far as the inner layer, and greatly 

 irritating the animal, which will sometimes deposit one or more new coatings of shell structure, so 

 as to cover up the little pores about to open into the inside. They probably also often cause the 

 destruction of oysters. These burrows sometimes appear on the inside as little prominences, 

 scattered over the surface. Masses of this Sponge, when full grown, measure a foot or more in 

 length, and contain stones as large as one's fist, as well as a large quantity of sand. " This 

 species is of a bright sulphur yellow color, and grows into hemispherical or irregular massive 

 forms of firm texture, the surface being covered with scattered, low, wart-like, soft prominences, 

 about an eighth of an inch in diameter, which contract when the Sponge is dried, leaving shallow 

 pits." 



Cliona svlphurea has the power of burrowing into submerged limestone as well as shells. A 

 case of this sort was brought to notice in 1878, when a wrecked cargo of marble was discovered 

 off Long Island, having lain there for several years. The pieces of marble taken up were 

 completely riddled by this Sponge to a slight depth. 



'Vineyard Sound Report, p. 421, 1871-'72. 



