ALCYONIUM. POLYPI. 



two separate substances ; and in the other five of one substance only variously com- 

 bined. 



SECTION I. 



Polypiferous masses composed of two distinct parts ; 1. of nu- 

 merous horny fibres, either in bundles, radiated, interlaced, 

 crossed, or felted together ; and 2. of a fleshy or gelatinous 

 pulp, which covers, envelopes, or attaches the fibres, con- 

 tains the polypi, and takes in drying a consistence more or 

 less firm. 



The fibrous portions of the masses formed by the polypi of this section are of va- 

 rious degrees of consistence, according to the species, and serve in place of an axis 

 for the support of the pulpy or gelatinous portion common to the whole individuals, 

 and the result of their joint labour. In some the fibrous portion becomes of exces- 

 sive tenuity, and is scarcely to be traced ; but the pulpy mass becomes on drying firm 

 and coriaceous, porous and celluliferous, according to the nature of the animal. 



Gen. 1. ALCYONIUM, Lam. 



Polypiferous masses polymorphous, soft or fleshy in the fresh 

 state, more or less firm, hard, or coriaceous when dried, com- 

 posed of very small horny fibres, interlaced and glued toge- 

 ther by a persistent pulp ; osculi generally apparent, and va- 

 riously disposed at the surface ; polypi commonly with eight 

 tentacula. 



A. vesparium, Lam. Fixed, erect, large, ovate-oblong, the apex ob- 

 tuse ; cavernous within ; osculi crowded on the surface. Inha- 

 bits African and Indian seas. -Lam. ii. 393. 



Gen. 2. GEODIA, Lam. 



Polypiferous mass free, fleshy, tuberous, hollow interiorly, firm 

 and hard in the dry state, with the exterior surface everywhere 

 porous ; a cluster of isolated openings larger than the pores 

 on the lateral face. 



G. gibberosa, Lam. Roundish, gibbous, with swellings and tuber- 

 cles. Lam. ii. 388. 



Gen. 3. TETHIA, Lam. Alcyonium, Mull. 

 Polypiferous mass knotty, subglobular, very fibrous interiorly, 

 the fibres subfasciculated, diverging or radiating from the 

 interior to the circumference, and agglutinated together by 

 a pulp ; cells in the crust horizontal ; osculi rarely percepti- 

 ble, caducous. 



T. cranium, Lam. Tuberiform, white, villous. Inhabits seas of 

 Norway. La m. ii. 386. 



Gen. 4. SPONGIA, Lam. 



Polypiferous mass fixed, soft, gelatinous, tenacious, very flexi- 

 ble, the cartilaginous matter supported by calcareous or sili- 

 ceous spicula ; pores very numerous, irregular. 



The investigations of Professor Grant have thrown much light on the structure 

 and formation of the animal of the sponge. The ploypiferous mass consists of an 



