BRYOZOA OR POLYZOA. 
119 
Examples : Fluslra (Fig. 61), Mcvihranipora (Fig. 65 a), Ony- 
cliocdla (Fig. 65 h). 
In many Bryozoa certain individuals are modified for 
special duties. Thus in the Cheilostomes the growth of the 
operculum has produced snapping beaks, called avicularia, 
and long movable bristles, called vibracula ; the positions 
occupied by these appendages can be detected in the fossils 
(Fig. 65). Sometimes individuals are set apart and modihed 
for reproduction, sometimes special pouches for the reception 
Fig. G4. — Oyclostoraatous Bryozoa from the Bathonian (Bradford Clay) of 
England, a, Slomatopora clichotoma, part of an encrusting colony, 
natural size, and magnified 25 diameters, h, Bcrenicca cempressa, an 
encrusting colony, natural size, and part of it magnified 12 diameters. 
(After J. W. Gregory.) 
of the developing eggs are attached to the chambers (Fig. 65 a). 
These modifications suggest explanations for the smaller 
chambers and tubes interspersed among the normal ones in 
the fossils of extinct Orders. 
AVe may now briefiy review the exhibited specimens. 
First are shown exani])les of the mode of occurrence of 
Bryozoan fossils, the rocks formed by them, and the habit 
of life of extinct species. 
The British series begins with some from the Ordovician 
rocks of AVales. These are so poorly preserved that they 
can only be determined by the help of better specimens from 
Gallery 
VIII. 
Case A4, 
West Side. 
