FLABELLARIA. POLYPI. 425 



mated, digitiform, apex furcated, subacute. Inhabits seas of Eu- 

 rope. Ellis, Zooph. pi. 58, fig. 6. 



Extinct species of Sponges are found in Britain in the chalk formation. 



Gen. 5. FLABELLARIA, Lam. CoralUna, Soland. 

 Polypiferous mass caulescent, flabelliform, incrusted, often di- 

 vided, with the expansions flattened, subarticulated, prolife- 

 rous ; stem short, cylindrical ; tissue composed of inter- 

 laced fibres ; articulations subreniform, broader than long, 

 with the upper margin rounded and sinuous. 



F.pavonia, Lam. (C.flabellum, Soland.) Stem simple, incrusted; 

 branches agglutinated ; flabelliform leaf incrusted, waved, sub- 

 lobed. Inhabits American seas. Ellis, Zooph. pi. 24, fig. A, B. 



F. incrassata, Lam. Stem short ; branches jointed, trichotomous ; 

 joints compressed, incrusted ; the inferior wedge-shaped, the up- 

 per reniform. Inhabits West Indian seas. Ellis, Zooph. pi. 20, 

 fig. d, d 1-3, D 1-6. 



Gen. 6. PENICILLUS, Lam. Corallina, Pall. 

 Polypiferous mass with a simple stalk, incrusted exteriorly, 

 filled interiorly with numerous horny fibres in bundles, and 

 divided at its summit into a cluster of filiform dichotomous 

 and articulated branches. 



P. capitatus, Lam. (C. penicillus, Soland.) Stem smoothly incrust- 

 ed ; branches fasciculate, and crowded into a thick, dichotomous, 

 articulated, and filiform head. Inhabits American seas. Ellis, 

 Zooph. pi. 25, fig. 4-6. 



SECTION II. 



Polypiferous masses branched like plants, composed of two kinds 

 of substance, a central and solid axis, and a fleshy incrusta- 

 tion, which covers and contains the polypi ; axis inorganic, 

 corneous or stony ; polypiferous crust when dried porous, 

 cellular, and friable. 



The Polypi of this section inhabit a fleshy crust surrounding an inorganic axis 

 formed by themselves. This fleshy covering is full of cells or pores, each the habi- 

 tation of an animal, possessing an individual and common life. The common dwel- 

 ling is raised from a flattened base attached to marine bodies, in the form of a tree 

 or shrub ; and from the general appearance of the branched and reticulated masses, 

 it was natural for the earlier observers to conclude that such objects belonged to the 

 vegetable kingdom. 



Gen. 7. CORALLINA, Lam. 



Polypiferous mass fixed, much branched, composed of a central 

 axis, and an interrupted incrustation ; axis filiform, inarticu- 

 lated, solid, cartilaginous, or horny ; incrustation calcareous, 

 dense, united at the surface without distinct cells, interrupted, 

 and as if jointed longitudinally ; polypi unknown. 



The Corallines have in general the appearance of small tufts or bushes beautifully 

 branched and attached by their own base, very much resembling plants in the man- 

 ner of their growth. The polypous inhabitants are very minute, and their cells on the 

 surface scarcely perceptible. M. Lamouroux, however, has observed minute fibrillae 



