1216 president's address. 



which possess a more rapid sub-marine slope, so that the lower 

 limit of the band of deti'itus extends far beyond the depths in 

 which the reef corals thrive, no such Barrier Reef will be formed. 

 He also thinks it probable that reef corals may commence to 

 build in depths greater than those usually assigned. 



The Rev. J. E. Tenison-Woods, F.L.S., in a Paper which was 

 read at our December Meeting, gives a very graphic description of 

 the Physical Geography and Geology of the State of Perak. The 

 lofty mountains rising to a height of 8000 feet, fronted by 

 precipices of limestone of various colours, and at their base 

 plains covered with dense jungle, must appear truly grand. But 

 of more practical interest are the extensive tin-bearing deposits. 

 Mr. Tenison-Woods states that the oi'iginal source of the tin 

 ore was the granites near their junction with the Palteozoic sedi- 

 mentary rocks. This mode of occurrence of the ore is in many 

 respects similar to that which has been observed in the tin mining 

 districts of New England in New South Wales. 



Dr. R. von Lendenfeld who joined the Society at the commence- 

 ment of last year, read over 30 Papers, mostly on the lower marine 

 animals of the Australian Seas. The experience and material 

 collected by him during his three years stay in different Australian 

 Colonies, is utilized in these Papers. The Hydromedusse and the 

 Scyphomedusse are finished, some new Ctenophorse have been 

 described, and a Monograph of the Australian Sponges commenced. 

 It may be hoped that the indefatigable Author will be able to finish 

 this in the way it has been begun, and so fill up a very large gap in 

 our knowledge of Australian animals. Many of his Papers dwell 

 on Comparative Morphology. He has discovered several interesting 

 facts of a general scientific interest. The development of one of 

 our large Jellyfish was found to be totally different from what was 

 hitherto known about their Metamorphosis. In a Paper on the 

 Geographical distribution of Medusse, the influence of ocean currents 

 on the Marine Eauna was illustrated. A most important discovery 

 was that of certain cells in Sponges which the Author considers as 

 Nervous elements. Their existence in the Sponges furnishes a 

 proof that these organisms are more highly developed Matazoa 



