156 CLASS III.— ORDER I. 



COAL. 



20. Spongia carhonaria. Unshapely, very stiff, 

 and black ; texture fibrous, reticulated, and very po- 

 rous. 



On the Millepora Alcicornis of the American 

 seas. 



INCRUSTING. 



21. Spongia incrustans. Mass forming a thin, fi* 

 brous, rose-coloured layer, on the surface of a fucus ; 

 texture reticulated, fibrous, loose, and irregular, with 

 rather large holes. 



Southern seas. 



AGARIC. 



22. Spongia ogaricina. Compressed, lobed, ses- 

 sile, reticulated, prickly, and osculated. 



Indian ocean. 



CRESTED. 



23. Spongia cristata. Even, upright, and soft ; 

 pores projecting and regularly placed. 



Coasts of France and England. 



COTTAGE. 



24. Spongia c?owM/7cw/fl. Convex; surface smooth, 

 but covered with little papillas ; very cellular within. 



Gulf of Genoa. 



GLOBULAR. 



25. Spongia globosa. Tough, and very cellular; 

 surface covered with simple or branching protube- 

 rances, elongated and rather stiif. 



Gulf of Genoa. 



