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Aleyonum digitatum and serpulae. The latter during the evening 

 expanded their beautiful polyps, some scarlet, some bright 

 blue.) 



From the living spongidae we will now turn to that of Fauna 

 buried beneath the stratified rocks of untold ages. From its 

 simple constructed life it took its dawn at a very early period of the 

 world's history. Fossil sponges may be found in every strata 

 from the Silurian to the latest deposits of the tertiaries. But on 

 the threshold of our enquiries into these fossil sponges we have 

 great dificultics to contend with, inasmuch as the delicate 

 organisation of many of them has been so metamorphosed by 

 pressure, infiltrations of silica, and other mineral substances, 

 as almost to destroy their original type. 



There is one specimen in particular to which I must call 

 your especial attention, and which, if one can judge from 

 e.xternal appearance, closely represents the common sponge of 

 commerce. I picked it up on the beach at Be.xhill, and on 

 passing the evening with my friend Dr. Bowerbank, the erudite 

 author of " British sponges," I placed it before him. He was 

 much struck with the appearance, pronouncing it unique, and 

 expressed a strong desire to see it again when polished. Alas ! 

 on my next return to Hastings with the chosen gem, I found 

 that he had passed away, and we visited his grave in the 

 picturesque churchyard of Holiington. The following is a 

 description of this rare specimen : — It is polished and partially 

 transparent, nearly tiiree inches in length, of an egg shape form 

 ratiier flatter below where we find the root ; from it the keratose 

 structure rises around the upper surface, anastamosing in all 

 directions. A number of fibrous like filaments terminating on 

 the surface may represent the pores and the tubes leading from 

 them, whilst five large distinct oscula are seen with radiating 

 fibrous structure extending from each, which after a time blends 

 with the striae proceeding from the adjoining ones, thus uniting 

 the whole in a reticulated net work. This specimen I have 

 named after our great authority on British sponges, *' Spongia 

 Bowerbankii." 



From the brief remarks I have made respecting the anatomy 

 of one species of the Porifera or Spongidse, you will now 

 understand that ail sponge life is entirely supported by currents 

 of water passing through their various systems, be they keratose, 

 calcareous, or siliceous. I regret to say that at present we have 

 no thorough classification on this subject to which I can con- 

 scientiously refer you. I have long been most anxious to arrange 

 my siliceous fossils in some definite order, but know not where 

 to apply for satisfactory information. I have visited the British 

 and other Museums, but came away without obtaining the 

 needful information. 



Mantel in his " IMedals of Creation," states, " I have 

 selected a few genera for the illustration of the subject, and 



c 



