TAIL MX. 



COLiALS OF THE SILURIAN FORMATION. 

 PLASMOPORA PETALirORMIS (p. 258). 



Fig. 1. Upper surface of a specimen found at Dudley, belonging to the Parisian 



Museum ; natural si/c. 

 la. Under surface of the same; natural size. 

 1/y. A magnified portion of the surface of another specimen,, found also at Dudley, 



and belonging to the Collection of Mr. John Gray, in which the calices 



are more distant, than in the preceding specimen. 

 \r. Vertical section of the specimen figured in ! and 1a. 



Plasmopoiia scita (p. 254). 



Fig. 2. Upper surface of a specimen from Dudley, in the Collection of Mr. John 

 Gray ; natural size. 

 2a. Calices, magnified. 



Propoha tubulata (p. 255). 



Fig. 3. Side view of a specimen from Wenlock, belonging to the Museum of Paris ; 

 natural size. 

 3<7. Calices, magnified. 

 Vj. Part of a vertical section, magnified. 



