PHYLUM PORIFERA. SIMPLE MULTICELLULAR ANIMALS 



101 



Order 2. Syconosa. Sponges of sycon 

 type, or sycon type at first, 

 changing into rhagon. Ex. 

 Scypha. 

 Class 2. Hyalospongiae. Mostly deep-sea spe- 

 cies. Siliceous spicules make up the 

 principal skeleton. The architecture is 

 very much openwork, with structural 

 parts often at right angles to each 

 other. The flagellate chambers are 

 consistently of a rhagon type, which 

 is only slightly modified from the 

 sycon type. 

 Order 1. Hexasterophora. Many spicules 

 are starlike in shape. Ex. 

 Euplectella, Venus's-flower-bas- 

 ket (Fig. 45). 

 Order 2. Amphidiscophora. No astral 

 spicules, instead there are am- 

 phidisks. Ex. Hyalonema, glass 

 rope sponge (Fig. 45). 

 Class 3. Demospongiae. Dominant t}'pe at 

 present; often massive and brightly 

 colored. The skeleton may comprise 

 siliceous spicules, spongin fibers, both 

 of these, or neither. The architecture 

 is always compact, with flagellate 

 chambers consistently of a highly de- 

 veloped rhagon type. 

 Order 1. Carnosa. Skeleton principally or 

 entirely organic colloidal jelly. 

 Small spicules sometimes pres- 

 ent. Ex. Chondrosia. 

 Order 2. Choristida. Skeleton principally 

 of spicules with 4 rays radiating 

 from a central point. Ex. Geo- 

 dia. 

 Order 3. Epipolasida. Somewhat spherical 

 sponges, with monaxon spic- 

 ules, which radiate from a cen- 

 tral region within the sponge. 

 Ex. Tethya. 

 Order 4. Hadromerina. Pin-shaped spic- 



ules. Some kinds excavate gal- 

 leries into calcareous material, 

 such as ovstcr shells. Ex. Cliona. 



Order 5. Halichondrina. Double-pointed 

 spicules, plumose or confused 

 arrangement. Ex. Halichondria, 

 the common "crumb of bread" 

 sponge. 



Order 6. Poecilosclerina. Many kinds of 

 spicules present. Often also 

 some spongin. Ex. Microciona. 



Order 7. Haplosclerina. As in Halichon- 

 drina, but with reticulate, topi- 

 cally fibrous skeletons. Ex. Hali- 

 clona, the "finger" sponge (Fig. 

 45). 



Order 8. Keratosa. No spicules; skeleton 

 of well-developed spongin fibers. 

 Ex. Spongia, the bath sponge 

 (Fig. 45). 



SELECTED COLLATERAL 

 READINGS 



de Laubenfels, M.W. A Guide to the Sponges 

 of Eastern North America. Univ. of Miami 

 Press, Florida, 1953. 



Hyman, L.H. The Invertebrates Through 

 Ctenophora. McGraw-Hill, New York, 1940. 



MacGinitie, G.E., and MacGinitie, N. Nat- 

 ural History of Marine Animals. McGraw- 

 Hill, New York, 19-19. 



Pennak, R.W. Fresh-Water Invertebrates of 

 the United States. Ronald Press, New York, 

 1953. 



Reese, A.M. Outlines of Economic Zoology. 

 Blakiston, Philadelphia, 1942. 



Wilson, H.V., and Penny, J.T. "The Regenera- 

 tion of Sponges (Microciona) from Disso- 

 ciated Cells." /. Exp. Zoo/., 56:73-147, 

 1930. 



