Other sorts of sponges are very abundant. The _Blonde Sponge_ of the Archipelago, often confounded with the Venetian; the _Hard Barbary Sponge_, called Gelina, which only comes by accident into France; the _Salonica Sponge_ is of middling quality; finally, the _Bahama Sponge_, from the Antilles, is wanting in flexibility and a little hard, and so is sold at a low price, having few useful properties to recommend it. Many species of _Spongia_ are described as inhabiting British seas, but none of any commercial value. Regarding them as apolypiferous zoophytes, Dr. Grant has pointed out certain principles of analysis on which they may be grouped, according to the arrangement of the horny fibres, the calcareous and siliceous spiculæ, and the distribution and formation of their pores and orifices. I. GROUPS OF WHICH THE CONSTITUENT STRUCTURE IS KNOWN. _Spongia._--Mass soft, elastic, more or less irregular in shape, very porous, traversed by many tortuous canals, which terminate at the surface in distinct orifices. Substance of the skeleton cartilaginous, fibres anastomosed in all directions, without any earthy spicula.--Example, _S. communis_ (Fig. 11 [2]). _Calcispongia_ (Blainville).--Mass rigid or slightly elastic, of irregular form, porous, traversed by irregular canals, which terminate on the surface in distinct orifices; skeleton cartilaginous, fibres strengthened by calcareous spicula, often tri-radiate.--Example, _S. compressa_ (Fig. 11 [6]). _Halispongia_ (Blainville).--Mass more or less rigid or friable, irregular, porous, traversed by tortuous irregular canals, which terminate at the surface in distinct orifices; substance cartilaginous, fibres strengthened by siliceous spicula, generally fusiform or cylindrical.--Example, _S. papillaris_ (Grant) (Fig. 11 [3]). _Spongilla_ (Lamarck).--Mass more or less rigid or friable, irregular, porous, but not furnished with regular orifices or internal canals.--Example, _S. fluviatalis_ (Linn.). II. GROUPS DEPENDING ON CHARACTERS OF SURFACE OR GENERAL FIGURE. _Geodia_ (Lamarck).--Fleshy mass, tuberous, irregular, hollow within, externally incrusted by a porous envelope, which bears a series of orifices in a small tubercular space.--Example, _G. gibberosa_ (Schmeiger). _Coeloptychium_ (Goldfuss).--Mass fixed, pedicled, the upper part expanded, agariciform, concave, and radiato-porose above, flat and radiato-sulcate below; substance fibrous.--Example, _C. agarisidioideum_ (Goldfuss). Fossils from the chalk of Westphalia. _Siphonia_ (Parkinson).--Mass polymorphous, free or fixed, ramose or simple, concave or fistulous above, porous at the surface, and penetrated by anastomosing canals, which terminate in sub-radiating orifices within the cup. _Myrmecium_ (Goldfuss).--Mass sub-globular, sessile, of a close fibrous texture, forming ramified canals which radiate from the base to the circumference. Summit with a central pit.