l xv i. PRESIDENT'S ADDRESS. 



arc the most interesting to the palaeontologist ; they are pro- 

 minent from the Silurian to the present day, and have contributed 

 largely to the calcareous beds cf every formation. They appeared 

 suddenly in great numbers in the Middle and Upper Silurian 

 beds, and continued right through to the Tertiaries, and unin- 

 terruptedly to our own times. The Chalk-beds contain two 

 typical deep-sea Corals, Bathycahus and Caryophyllia, similar to 

 those now living. Caryophyllia cylindrica is now found in our 

 seas without any modification. During the Eocene age, Corals 

 were largely represented north of the Pyrenees, in Switzerland, 

 Bavaria, the Maritime Alps, the Crimea, Egypt, Syria, Arabia, 

 and the West Indies. Owing to changes of climate during the 

 Pliocene Age they became of less importance in Europe and 

 gradually moved southward. Corah are marine, usually frequent- 

 ing shallow- water, near the shore, and among the Alga, they are 

 found usually in the Laminarian and Coralline zones. The 

 extinct palaeozoic Graptolite, a sub-class of the Hydrozoa had a 

 nearly universal distribution. With the exception of the Hydra 

 (the fresh-water Polype) and Cordylophora, all the Hydroids are 

 marine and like the Corals, live among the rich vegetation of 

 Algce near the shore. Next in order are the Medusa, character- 

 ised by their discoidal forms, and the mode by which they propel 

 themselves through the sea. The body is of a soft jelly-texture, 

 no skeleton, external or internal. The delicacy of their structure 

 and facility to decompose prevented fossilization, but impressions 

 of them have been preserved in the Lithographic beds of Solen- 

 hofen (Kimmeridge). Many closely allied forms are taken in the 

 seas at the present day. The disc is umbrella-shaped, mouth on 

 the under- side surrounded by radiating canals or pockets. 



Echinodermata, the next in succession, comprises the Sea- 

 Urchins, the Star-Fishes, the Brittle- Stars, the Sea-Cucumbers, 

 &c. They are furnished with an exoskeleton of carbonate of 

 lime, and are well preserved in a fossil state. " Each plate, 

 spine, and joint are mineralogically and optically, as it were, made 

 out of a single crystal of calcite, having its principal axis 

 perpendicular to the plane of the plate, or parallel to the axis of 



