CHALK WITH BELEMNITELLA QUADRATA. 307 



Stnihan's description thereof. The fine, white, powdery portion of 

 the Taplow rock consisted nearly entirely of coccoliths, discoliths, 

 and rhabdoliths, unaltered, and of carbonate of lime similar to 

 those in the normal white Chalk. The minute, translucent, angular 

 fragments in the granular portion were shown to be pieces of fish- 

 bone by the occurrence in them of true bone lacunae and canaliculi, 

 and many were likewise thickly penetrated by borings of algie or 

 fungi. Similar fragments were present in the DouUens and Ciply 

 material, but their osseous nature had not previously been recog- 

 nized. The minute phosphatic pellets were probably coprolites of 

 small fishes. The evidence pointed to the exuviae of fishes as the 

 source of the phosphatic materials in these deposits. 



Mr. WuiTAKER said that, from the regularly bedded character of 

 the phosphatic chalk, one would have expected it to occur for some 

 distance from the pit ; but no trace could be seen either of the 

 phosphatic beds or of the flintless Chalk in which they occur. It 

 seems as if the topmost Chalk here occurs only over a small area, 

 having been eroded elsewhere. That this was the case to the west 

 and north-west had been surmised by Mr. Jukes-Browne (" Geology 

 of London," vol. i. pp. 76-78, 1889), from an examination of fossils 

 collected from the various pits ; but the thinning-out of the top 

 Chalk seems to be more sudden than was expected, and not only in 

 the above directions but all round from Taplow. Mr. Strahan's 

 discovery showed how much there might remain to be done, even 

 with regard to so well-known a formation as the Chalk. 



Prof. JuDD remarked upon the interesting nature of the micro- 

 scopic borings described by Dr. Hinde. His attention had been of 

 late directed to the subject in studying oolitic grains, both recent 

 and fossil. Both Mr. G. Murray and Dr. Scott were of opinion 

 that these borings in shells were produced by the plants that 

 had been so well described by the distinguished French phycologist, 

 Bornet. A very acute observer, Mr. F. Chapman, had noticed 

 that shell-fragments in the Gault frequently exhibit these borings, 

 and Dr. Scott had been able to identify several of Bornet's genera, 

 founded on recent specimens, as being represented in these Cre- 

 taceous shells. Bornet believed that these boring algas perform a 

 very important part in the economy of nature, by bringing about the 

 destruction and solution of shell-fragments. 



The President, alluding to the geological and economic interest 

 of the discovery described in the paper, remarked that though the 

 area occupied by the phosphatic layers seemed to be small, there was 

 good reason to hope that somewhere else in the Upper-Chalk dis- 

 tricts the same or similar bands might yet be found. The search 

 for such deposits would now be stimulated by the information so 

 fully supplied by the Author, who himself would no doubt follow up 

 his observations at Taplow by a thorough examination of the 

 higher members of the Chalk in the East of England. 



