58 SPONGES. 



The Officinal Sponges, which are divided into the finer and more 

 compact or '• Turkish Sponges," which are the dearest, and the coarser 

 and less compact or " Honeycomb Sponges," which are the cheapest, 

 gi-ow on the rocks throughout the Torrid and Temperate Zones under 

 more or less modified structure, but the most marketable hitherto found 

 come from the Levant and the neighbourliood of the Bahama Islands, in 

 the West Indies, respectively, where they are obtained by divers, v/ho, 

 cutting them off, bring them to the surface in baskets ; after which the 

 soft parts are diained away in the sun and the imperishable skeleton 

 having been finallj' cleansed is thus fitted for sale in the marketable parts 

 of the world. 



Sponges are so easily propagated by '• cuttings," when properly treated, 

 that this has been taken advantage of in the Adriatic for growing the 

 Of&cinal species. 



At present it is not determined where the Spongida should be placed 

 in the animal scale, although, of course, very low down, but when more 

 is known of their structure and species, those alliances will be found to 

 which I have before alluded, and their present enigraatical position thus 

 demonstrated. 



Of the important part that the Spongida have played in the geolo- 

 gical history of the earth there is no longer any doubt. Their remains 

 occur abundantly from the Silurian* epoch down to the present time, and 

 when it is remembered that a narrow dredge passing over the deep sea 

 bed of the Atlantic for a few miles, forming a kind of path-way through 

 this vast area like a garden walk, comes up literally crammed with the 

 remains of siliceous sponges, it not only gives us some idea of their 

 pleutifulness in this dark and dismal abode, but accounts for the immense 

 quantity of their debris in some of the Mesozoic Strata, and the influence 

 which their Silica when set free has uudoul^tedh' exerted iniuerally 

 over the composition of these strata. 



Brief as this description of the Spongida is, it has been thought 

 desirable to premise something of the kind, before giving the following : — 



List of Sponges dredged by the Birmingham Natural History and 

 Microscopical Society, Falmodth Excursion, 1879, depth 15 — 50 



FATHOMS. 



N.B. — Unless otherwise mentioned, the names of all the following 

 sponges are those under which they appear, and are illustrated in 

 Dr. Bowerbank's "British Spongiadse," Vol. III., 1874, as this is the 

 work most likely to be generally possessed in England. 



♦ In course of the discussion which followed the reading of the above paper, 

 Mr. W. J. Harrison remarked that the spoupes had even a higher known antiquity 

 than had been assigned to them by Mr. Carter, for their fossil remains had been 

 discovered in rocks of Cambrian age. The researches of Dr. Hicks (see " Quart. 

 Joum. Geol. Soc") had brought to light four species of sponges from the Menevian 

 Beds of St. David's, in South Wales, and even from strata l,r>00ft. lower (corres- 

 ponding to the Longmynd rocks) he had obtained two species, which had been 

 named Protospongia fenestrata and P. major. Hence, as the organic origin of the 

 Laurentian Eozoon was still disputed, the sponges were entitled to rank among the 

 oldest known fossils. 



