44 BRITISH PALAOZOIC FOSSILS. [Potyzoa. 
4th Class, POLYZOA. 
The Polyzoa of Thompson of Cork form a peculiar class of Fadiata, subsequently named Bryozoa, 
by Ehrenberg, from their moss-like growth, and Ciliobrachiata by Farre, from their tentacles (unlike those 
of other polyps) being covered with vibratile cilia; they are of far higher organization than the Zoophyta, 
with which they were long confounded, although individually they are all very much more minute; by their 
aggregation, however, they form delicate but moderately large coralla. Each individual is contained in a 
long cylindrical, or short oblong or ovate cell, never divided by transverse, nor radiating, lamellae, composed of 
the more or less hardened outer integument of the animal; the upper portion, or that near the aperture, 
always remaining flexible and continuous with the neck of the inhabitant, and being inverted with it when 
it contracts within the cell. The mouth is at the anterior end, surrounded by about twelve long tubular 
stiff tentacula, covered with vibratile cilia, causing a perpetual current of water. The mouth selects the 
proper particles of food brought by the inner current, and passes them to a contractile pharynx, leading 
to a large cesophagus, ending in a muscular gizzard, in which the food is comminuted before passing into 
an elongate stomach studded with brown hepatic glands; a very straight intestine extends from the stomach 
to the anus, which is near the mouth at the base of the tentacles. This complexity of the digestive 
system induces many modern naturalists to remove the Polyzoa from the Radiata to the Mollusca, placing them 
next the Zunicata. Respiration is usually referred to the ciliated arms. No distinct circulation, nor nervous 
system, has yet been recognised, but the muscular system is fibrous and well developed; one set of muscles 
for retracting the creature within its cell arises from the inner wall, and is inserted into the base of the 
tentacles ; another set arises from the bottom of the cell and is inserted into the stomach; other shorter 
fasciculi retract the soft edge of the cell by extending from it to the inner edge of the hard portion. 
The animal is protruded by the action of a few circular muscular fasciculi compressing the fluid parts. 
Reproduction is both by buds and ciliated free locomotive gemmules, neither of which originate from any 
special organ, but are developed from the parietes of the cell; the former from the outer, the latter from 
the inner surface. The gemmules becoming free are developed in the cavity between the cell and the 
body of the polyp, which they kill by their growth, finally escaping through the aperture. 
This class is divided into the following families:—1, Kscharide ; 2, Tubuliporide ; 3, Myriaporide ; 
4, Asterodiscide ; 5, Halcyonellide. 
Ist Family. ESCHARID. 
Polypidom free or encrusting, never rooted by a calcareous mass; substance stony or crustaceous, 
seldom flexible; cells shallow, oblong, or ovate, often provided with an operculum, capable of being 
closed by special muscles. 
Genera :—l, Eschara; 2, Escharina; 3, Berenicea; 4, Ptilodictya; 5, Escharites; 6, Escharoides ; 
7, Melicerita; 8, Tilesia; 9, Membranipora; 10, Flustra; 11, Discopora; 12, Ocellaria; 13, Cellepora ; 
14, Apsendesia; 15, Cellaria; 16, Vineularia; 17, Intricaria, &e. 
Genus. BERENICEA (Zam.) 
Gen. Ohar,—Corallum encrusting foreign bodies, composed of a very thin, calcareous, foliaceous base, 
bearing numerous ovate, distinctly separated cells, not piled; aperture round near the broad anterior end ; 
cells disposed in an obscurely radiated arrangement. 
The cells resemble Cellepora, but are not piled; they also resemble, in some measure, the cells of 
Stictopora (Ptilodictya) but are parasitic and confined to one side; they differ from Discopora by each 
cell being separated by a small space from its neighbour. 
