IHSTmr.l TION <>|- Sl'ONV.KS. 



Australia allords a tew forms, and I have heard, though I cannot substantiate the I'M.-I. of 

 some species on the Atlantic coast of liraxil. Bermuda also lias a few of tht> commeicial kinds, 



which, according: to Mr. (mode's n port, anil the unite of specimens forwarded, arc n li COMI-I-I 



than (lie Key West, darker in color, ami, in tact, junt about intermediate betw.-.-n these and those 

 of Australia. They are occasionally found in the stores, hut, as a rule, are used .nils liy the 

 lislierincn themselves, about their boats, the Bahama Hjwnges being preferred for domestic 

 imrposcs ly the inhabitants. 



The true Sp,>H<,i,r are all shallow-water forms. In the Mediterranean, according to Kckhel, 

 they are not found below thirty fathoms, and in onr own seas about the same, probably, though 

 not tished to greater than five fathoms. The greater part of the fishery is accomplished between 



the depths of three and twenty feet, according to the report of Dr. Palmer, from \vh these 



remarks are principally derived. The commercial grades coincide very closely here and in 

 Kurope, but it is quite easy to show that each of them may be considered a distinct species, if one 

 has an inclination to multiply in this direction. The three grades [of American Sponges]. Glove 

 SjMHigc iSiHHtiiiii officinal!*), subspecies tubulifera, Wool Sponge (Spongia r//i/m), subsides go*- 

 xi/i>inii, and Yellow and Hard Head, both under the name of (Spongia agaricina), subspecies ,-,,, 

 toxin, correspond with remarkable accuracy to the three principal grades of commercial Sponges 

 in Kuropc. These are the Bath Sponge, Spongia officinal!*, the Horse Sponge, Spoiii/iti M/iiiim. and 

 the Xiinocc.a Sponge, Spongia agaricina. This result, in which three species appear on both sides 

 of the Atlantic, as representing alone the marketable, qualities of the genus Spongia, becomes 

 of double interest when these varieties, or local species, as they might be called, are compared 

 with one another. It is then found that the aspect of the surface is closely similar in each 

 of the three; that subspecies tubuUfera represents Spongia offieiiutli*, subspecies goiutypina offsets 

 H/ionf/ia equina iu the same way, and, lastly, subspecies corloitia has the same relation to Spongia 

 iii/nricina. 



"The whole group of Keratosa is confined to seas in which the differences observable 

 between the winter and summer isotherms are not excessive. None are found north of Cape 

 Hatteras and the island of Bermuda, and doubtless a similar limit occurs to the southward of 

 the equator. 



"The liner skeletons of the Keratoza, those of the genus Spongia, are only to be sought in 

 the intermediate zone, where the waters are of equable and high temperature. Again, in examining 

 the species of this genus with relation to each other, it becomes equally evident that they arc 

 finest and most numerous in archipelagoes or off coasts which are bordered by large numbers of 

 islands or long reefs, or in sheltered seas. 



"The Sponges near Nassau lie on reefs very much exposed to the action of the waves, often 

 thirty miles from land, and always in currents, sometimes running three or four miles an hour. 

 Such currents are usual wherever groups of islands confine the tide water within certain definite 

 channels, and they have also the effect of concentrating the floating food in the channels, or 

 wherever tides meet. Both of these conditions are essential to successful sponge growth, namely, 

 a continuous renewal of aerated water and a plentiful supply of food, and are probably partially 

 the cause of their abundance in such places. 



"The shallow-water Sponges arc coarser than the deep-water forms. This is probably due, in 

 part, as in other species, to the quantity of sediment, which is, of course, less in deep than in 

 shallow water, as, for example, at Key West in the winter time. I am informed that no fine 

 qualities of any Sponges are found within the limits of the milky water, but all the liner qualities 

 of the marketable kinds in the deepest water in which the species occur, except perhaps in the 



