1 66 TJie Commercial Products of the Sea. 



coloured and coarse variety of the Spongia equina is 

 obtained, called the gerbis sponge. 



The distribution indicates the naturalness of the three 

 species, and shows also that the dealers have to do with a 

 vast variety of forms. They can, however, pick out the 

 three species and their varieties without hesitation, and I 

 was amused and interested at finding that the method 

 pursued was precisely similar to that which I had been 



FIG. 5. 



rKr&y'KSrm 



e 



Outer surface of different kinds of sponge (natural size). A, Cup-shaped 

 variety ; u, honeycomb sponge ; c, toilet sponge ; D, Bahamas sponge, partly 

 in sections, showing projecting extremities and internal tubular character. 



obliged to adopt in distinguishing empirically the various 

 sub-species and species of Spongia. They are led mainly 

 by the general aspect of the surface. This has a distinct 



