330 [Proc. B.N.F.C. 



concretions of quartz. Herein lay the secret of crystal- 

 growth, which was yet a mystery. The agate-tubes were also 

 a mystery to him; he called them ''tubes," or "points of 

 arrest." The late Dr. Heddle, of St. Andrews, contributed 

 much to our exact knowledge of agate-structure. He 

 examined several thousands of agate-sections, and, after mucb 

 study, came to the conclusion that agates were derived from 

 the decomposition of the mother-rock by the percolation of 

 meteoric waters (cold) containing carbonic and humic acids 

 which had the power to decompose the rock-forming silicates 

 with formation of free silica. The question of the geological 

 age of agates was still unsettled. Undoubtedly agates bore 

 the same relations to the basic mother-rock as the zeolitic 

 minerals did to their mother-basalt, and if the zeolites had 

 been secreted from hot solutions, so also had agates. There 

 was also undoubtedly a law governing the order of deposition 

 of the minerals in an agate-cavity, and this law was almost 

 identical with that governing the order of crystallisation of 

 the minerals in the mother-rock. 



Mr. W. Gray and Mr. R. Welch criticised the paper. 



Both papers were fully illustrated by lime-light views, the 

 lantern being in charge of Mr. A. R. Hogg. Afterwards the 

 members came forward to the table, where Messrs. Bell and 

 Strachan had a large series of specimens, to which they had 

 referred in their papers, and these were examined with great 

 interest. The election to membership of Messrs. William 

 Greenhill, Samuel Sinclair, and W. J. Porritt brought the 

 proceedings to a close. 



" SHARKS* TEETH FROM LOCAL CRETACEOUS FORMATIONS." 



The Wednesday evening meeting of the Club was held in 

 the Museum, College Square, on 22nd February — the Presi- 

 dent (Mr. W. J. Fennell, M.R.I.A.I.) presiding— when Mr. 

 Robert Bell read a paper on " Sharks' Teeth from the Local 

 Cretaceous Formations," in which he said: — The specific de- 

 termination of the detached teeth of sharks is little more than 



