SPONGES. 



VALUE OF SPONGES. There are six species of sponges valued in 

 commerce ; three are found in America, in Key West and the Baha- 

 mas, the others coming from the Mediterranean and Red Seas. Nearly 

 all the flints are the remains of ancient sponges. 



Specimens for Study. Sponges are difficult to keep in 

 the aquarium. In our Northern fresh-water ponds, the 

 Siphydora is common, and, in streams, the Spongilla, while 

 various kinds can be found along the coast. In default 

 of living specimens, the common toilet-sponge should be 

 used, and sections made with a razor for examination 

 under the microscope. 



Works on. Sponges for further reference. 



" The Glass Sponges," by Rev. Samuel Lockwood, in " Popular 

 Science Monthly," vol. iii, p. 529 ; "The Common Fresh-Water Sponge, 

 SpongHld" by Professor W. C. Williamson, in " Popular Science Re- 

 view," January, 1868 ; " North American Poriferse," by A. Hyatt, m 

 "Memoirs of Boston Society of Natural History"; "Life Histories 

 of Animals," by A. S. Packard, Jr. ; " The Atlantic, and Depths of 

 the Sea," Sir Wyville Thomson. 



A Syrian sponger. 



