PORIFERA 



S3 



Ancestry and Relationship to Other Phyla. — Porifera are nearer 

 the Protozoa than are any of the other types of Metazoa. The 

 collar cells resemble certain colonial choano-flagellates . 



While the sponges somewhat resemble the Coelenterata, in 

 having a fixed mode of life, in budding, and in having a large gastro- 

 vascular cavity, the mode of formation of embryonic layers in the 

 two groups shows radical dissimilarity. They are probably derived 

 separately from the Protozoa. 



References on Sponges 



Cobb, J. N. 1902. The Sponge Fishery of Florida in 1900. Report of 



U. S. Fish Com. 

 Davis, R. O. E. 1912. Sponge Spicules in Swamp Soils. Circ. No. 67, 



Bureau of Soils, U. S. D. A. 

 Flegel, Ch. 1908. The Abuse of the Scaphander in the Sponge 



Fisheries. Bull. U. S. Bureau Fish., Vol. 28. 

 Moore, H. F. 1908. The Commercial Sponges and the Sponge Fish- 

 eries. Bull. U. S. Bureau of Fisheries, Vol. 28, part i, pp. 403, 



407-1 1, 426. 

 Tressler, D. K. 1923. Marine Products of Commerce. Chem. Cat. 



Co., N. Y. 

 Wilson, H. V. 1910. Development of Sponges from Tissue Cells 



Outside the Body of the Parent. Bull, of the Bur. of Fish., Vol. 28, 



pp. 1265-1271. 

 Wilson, H. V. 1911, Development ot Sponges from Dissociated Tissue 



Cells. Bull, of the Bur. of Fish., Vol. 30. 

 Consult, also, papers by Galtsoff, P., U. S. Bur. Fish. 



